■ 1 ilL MU UJ1 AH 10 M 
OF 
NATURAL AND OF ARTIFICIAL LABOR 
IN 
NARROW PELVES. 
WILLIAM GOODELL, A.M., M.D., 
BY 
CLINICAL PROFESSOR OF THE DISEASES OF WOMEN AND OF CHILDREN IN THE 
UNIVERSITY OF PENNSYLVANIA. 
" Opinionum commenta delet dies, natural judicia confirmat." 
Cicero, Da Naturu. Deorum. 
Extracted from the Transactions of the 
INTERNATIONAL MEDICAL CONGRESS, 
Philadelphia, September, 1876. 
PHILADELPHIA: 
1877. PHILADELPHIA : 
COLLINS, PRINTER, 
705 Jayne Street. THE MECHANISM OF NATURAL AND OF ARTIFICIAL 
LABOR IN NARROW PELVES. 
In studying the mechanism of natural and of artificial labor in narrow 
pelves, let us first inquire what is meant by a narrow pelvis, and what 
are its kinds. 
A pelvis with a true conjugate (conjugata verci) measuring less than four 
inches constitutes a narrow pelvis. For, although the biparietal diameter 
of the average foetal head at term measures less than four inches, the 
working space between the promontory of the sacrum and the symphysis 
of the pubis is lessened by double the thickness of the uterine wall, and 
by double that of the vesical wall. While, therefore, the actual conju- 
gate is ample for an average head to pass, the virtual conjugate may be 
too small. Thus, according to our best authorities, a standard head in a 
pelvis measuring in its conjugate 3.75 inches-viz., half an inch less than 
that of the average-sized pelvis-constitutes a difficult labor. 
A spontaneous delivery is not impossible under such circumstances, 
but the forceps will usually be needed ; sometimes, indeed, craniotomy. 
Every line below this measurement greatly increases the difficulties of* 
parturition. For instance, out of thirteen vertex presentations in pelves 
measuring at the least 3.75 inches, Dubois had three cases of craniotomy 
or of cepbalotripsy. In conjugate diameters between 3.75 and 3.1 inches, 
he had ten presentations at term of the vertex, and one of the face. Of 
these, two ended spontaneously, two were delivered by the forceps with 
the death of one child, and seven needed the cephalotribe.1 Baudelocque 
contends that out of five hundred children at term and of average size, 
hardly one will be delivered alive through a pelvis of three inches. To 
this, Dezeimeris2 adds that one of 3.25 inches does not give much better 
results, and that one of 3.5 inches also offers to the child a very dangerous 
passage. Joseph Clarke gives,3 as the result of an experience of 14,077 
cases of labor, that " three and a half inches is the least diameter" through 
1 Management of Labor in Contracted Pelves. By Wm. H. Jones. This author, it is 
true, makes these cases occur respectively in pelves whose conjugates measured "over 3.5," 
and " between 3.5 and 3 inches." But since he has adopted the classification of Dubois, 
these figures seem to me incorrect. For Dubois's first and second categories of deformed 
pelves are those in which the conjugates measure respectively, at the least, 3.75 inches 
(au moins 9.5 centimetres), and between 3.75 and 3.1 inches (au plus 9.5 centimetres et 8 
centimetres au moins). This information I get second-hand from Cazeaux, arid not from 
Dubois, whose thesis is beyond my reach. 
2 Dictionnaire en 30; Art. Accouchements Pr6maturees, p. 427. 
. 3 Contributions to Midwifery; by T. E. Beatty, p. 23. (jUOl)ELL, 
which he has known "a full-grown foetus to pass entire." Chailly-IIonore 
says,1 "The forceps will frequently extract a living child through a con- 
jugate of over nine centimetres (3.54 inches), sometimes, indeed-although 
this is very rare-under this size." From these facts, the broad rule may 
be laid down that, when the short diameter of the brim does not exceed 
the biparietal diameter of the child's head, the unaided efforts of the 
mother will in general be inadequate to effect a safe delivery, and that 
even with instrumental aid the life of the child will be greatly imperilled. 
The most common kinds of narrow pelvis are three in number:- 
(1) The simple, flat pelvis, or conjugate narrowing with correlative 
transverse widening. 
(2) The generally and uniformly narrowed pelvis, in which all the 
pelvic diameters are symmetrically shortened. 
(3) The generally narrowed, flat pelvis, which combines the bone-lesions 
of the other two, but in varying proportions. 
Of these three varieties, the one most commonly met with is the 
simple, flat pelvis, in which the lesion is limited mainly to the brim and 
to its posterior half. Practically the obstruction is a marginal one, and 
is confined to the sacral pole of the conjugate diameter. In the second 
variety-or the generally and uniformly narrowed pelvis-the obstruction 
is not a marginal one, nor of limited area, but diffused over every plane 
of the pelvic canal. In the third variety, the obstruction depends upon 
the preponderance of conjugate or of transverse narrowing, and is, there- 
fore, either mainly at the brim and marginal, or mainly in the pelvic 
canal and diffused. 
Since "Art is the imitation of Nature, and those will best succeed in 
any science who closest watch her operations,"2 let us next note the 
mechanism of an unaided head-first labor in these different kinds of 
narrow pelvis. 
In the generally and uniformly narrowed pelvis, the mechanism is very 
analogous to that which takes place in the standard pelvis, but is of course 
attended with more delay. The head enters the brim synclitically and 
with the normal obliquity-that is to say it engages in one of the 
oblique diameters of the brim, but without lateral (Ntegele's) obliquity. It 
will also be strongly flexed (Roederer's obliquity), because the resistance at 
the brim is equal on all sides, and the shorter hind-arm of the head-lever 
must therefore descend. The head also begins to flex at a higher plane 
of the pelvic cavity than in the standard pelvis. For flexion in the latter 
is chiefly brought about by the resistance of the os uteri; in the former 
by the more highly situated brim. During the descent of the head, the 
synclitic movement is preserved except in so far as vertical or lateral 
shearing interferes with it. Since the absolute conjugate narrowing is 
rarely great, and the general narrowing is symmetrical in all directions, 
the furrows or the fractures of the cranium are by no means so common 
as in the other varieties of deformed pelvis. But, when present, they 
usually start from the boss of the parietal bone and run more or less 
parallel to the sagittal suture, as in cases of fracture reported by Lize3 
and D'Outrepont,4 and one of depression of the skull by Danyau.5 It 
must, however, be borne in mind that, while the bone-furrow always 
1 Accouchements; Paris, 1867, p. 649. 
2 The Present State of Midwifery in Paris; by A. Tolver, 1770, p. 22. 
3 Union M6dicale, F6v. 1860, p. 295. 
4 Journal de Chirurgie, par Malgaigne, 1843, p. 41. 5 Ibid., p. 49. L AB U K 1 IM B A It it u vv i uyjuo* 
indicates the transit-line, the fractures do not, as they may radiate from 
it in every direction. 
When left to the unaided efforts of nature, the typical mechanism of 
a head-first labor in the flat pelvis, or in one whose brim is narrowed 
mainly in its conjugate diameter, is as follows:-The hind-head offers 
its biparietal diameter at the conjugate, but cannot enter. The resist- 
ance being nearer to the occipital end of the head causes extension, and 
the fore-head dips. As the fore-head descends, the sagittal suture, 
losing its Solayres and Roederer obliquities, becomes transverse in two 
senses-viz., it lies in the transverse diameter of the brim, and with the 
two fontanelles on the same plane. The shorter and more compressible 
bitemporal diameter-that is to say, the upper or vault portion of each 
temporal region near the coronal suture-reaches the conjugate, and is 
driven into it, by the changed direction of the propelling force, which, 
acting through the vertebral column, is now thrown out of its perpen- 
dicularity to the base of the skull, and so bears at an angle directed to 
the forehead. Thus the head is nipped, bent in on its sacral side, and 
moulded to the promontory. Sometimes it is the bicoronal (the bifronto- 
temporal) diameter which is nipped. Hence the frequency of face-pre- 
sentations in narrow pelves-a frequency, according to Michaelis, eight 
times greater than in normal pelves.1 Hence, also, the ease with which 
the anterior fontanelle is reached, and the corresponding difficulty with 
which the finger touches the posterior fontanelle. 
The resistance is now at a point nearer to the fore-head than to the 
hind-head, and the latter, therefore, begins to descend, but with the 
biparietal diameter to one side of the conjugate diameter. But the 
resistance of the iliac margin of the brim to the descent of the hind-head 
causes that portion of the cranium to expand and to mould itself to the 
corresponding sacro-iliac space. It also tends to shove the whole head 
over to the forehead side of the pelvis. In a generally narrowed, flat 
pelvis with absolute transverse shortening, this displacement in the 
direction of the occipito-frontal diameter may go on until stopped by 
the impact of the forehead on the opposite ilium. The head, therefore, 
passes the conjugate, not vertically in the bicoronal or the bitemporal 
diameter which first engaged, but along a transit-furrow running some- 
what obliquely from that portion of the vault near the coronal suture to 
the base posteriorly, that is to say, in the resultant of three forces - 
flexion, uterine propulsion, and occipito-frontal displacement in the 
transverse (bisiliac) diameter of the brim. In proportion as the head 
descends, it becomes more and more flexed, and the biparietal diameter, 
which passed the brim to one side of the conjugate, will, at a later stage 
of labor, be found almost directly under the promontory. It must, how- 
ever, be remembered that, since all the transverse diameters of the pelvic 
cavity are also lengthened out, the head usually descends to the floor of 
the pelvis with less flexion than in the normal pelvis, and anterior 
rotation of the vertex is proportionally delayed. 
Thus, from the mechanism of natural labor in this kind of pelvis, it 
will be seen that the head enters the brim in a state of partial extension, 
or at least in a state midway between flexion and extension, and passes 
the short pelvic diameter by a short and most compressible cranial 
diameter. Further, the head usually passes the brim with also a lateral 
obliquity. Before the engagement of the head, the sagittal suture in a 
1 Clinical Lectures by German Authors, New Sydenham Society, 1876, p. 302. typical case will be found very close to the promontory. To engage, the 
head must cant over the edge of the promontory; and during the first 
stage of descent this suture approaches the pubis. Later on, it begins to 
return towards the sacrum. This last movement is owing partly to the 
moulding of the posterior side of the head, and partly to the greater 
resistance to descent at the sacro-vertebral angle, while the pubic margin 
of the brim offers a smooth and glib surface. The head, therefore, pivots 
on the promontory as a centre of motion, and, as it were, rolls over into 
the pelvic cavity. It " doubles the promontory," as our honored Presi- 
dent, Dr. Barnes, so happily expresses it. 
After such an unaided delivery, or after an artificial delivery in which 
the application of the forceps is delayed until the head has been driven 
past the brim, the cranium exhibits two very characteristic shears. In 
the one, there is a bending in of the sacral side of the head, and a bulging 
out of the pubic side-it is kidney-shaped. In the other, an equitation 
of one parietal bone over its fellow-usually the anterior over the pos- 
terior. The site of the pressure-furrow, or of the bone-lesion, varies with 
the size and the position of the head, and with the shape of the pelvis. 
It is not found at one of the poles of the biparietal diameter, and more 
or less parallel to the sagittal suture, as in the uniformly narrowed 
pelvis in which the vertex dips ab initio, but at the forepart of one 
parietal bone, close to and more or less parallel to the coronal suture. 
Often it lies directly over this suture, overlapping both frontal and 
parietal bones, and sometimes on the frontal bone alone. 
When the disproportion between the size of the head and that of the 
brim is relatively great, or when the conjugate is short and the head 
unduly ossified or bullet-shaped, engagement is often delayed. Under 
such conditions the head does not at once become fixed by the preliminary 
dip of the anterior fontanelle, but it coys at the brink of the brim without 
entering. Perched on the sacral shelf, it swings backward and forward, 
and see-saws with every foetal movement. The finger will find the sagit- 
tal suture usually close to the sacrum, and the posterior fontanelle now 
in front and now behind the transverse diameter of the brim ; now dip- 
ping into the inlet, anon tilting up out of it. It is momentarily fixed 
by each uterine contraction, and then is the time to take the position. 
This cranial play usually ends before long, and that by the adjustment 
and moulding of the bicoronal region to the conjugate, and by its conse- 
quent engagement and descent. And this may be hastened, as the late 
Edward Martin has shown,1 by turning the woman over on to the side 
towards which the forehead looks. The breech of the child then sags 
over to the same side, the hind-head is lifted out of the brim by the 
leverage of the spinal column, and the fore-head sinks in more deeply. 
Whenever this dipping of the fore-head does not happen, delivery without 
artificial aid will be indefinitely delayed. 
In the foregoing description I do not pretend to have labelled all the 
natural processes involved, nor to have codified every law which governs 
the cranial movements in narrow pelves. Nor do I contend that the 
anterior fontanelle always dips, for the head may be a small one, or the 
cranium a yielding one, or other disturbing elements may intervene. 
But from a study of the writings of Schroeder, Spiegelberg, Martin, and 
Otto de Haselberg, and also from patient bedside observation, I believe 
that the above mechanism is in the main correct-it certainly best ex- 
1 Prager Vierteljahrsschrift, 1868, Band ii., Analect, S. 76. LABOR liS iNAKKOW FJiLVES. 
plains the behavior of the head. Since, however, the truth is not always 
truthlike, and since the flexion of the head with the dip of the hind- 
head has hitherto been taught as the mode of engagement, a few more 
words on this point are needful. 
If, in a pelvis narrowed mainly in its conjugate diameter, the hind- 
head always dips, and the vertex first enters the brim, as contended by 
Hodge and by many others, what explanation can be offered for the 
indisputable fact that the anterior fontanelle, at the outset of labor, is 
so commonly on the same plane with the posterior fontanelle, or even on 
a lower plane? How interpret the well-known frequency of face pre- 
sentations in narrow pelves? Again, if it can be shown, that, after such 
unaided labors the pressure-marks or other coarse cranial lesions are found, 
not at one of the poles of the biparietal diameter, which is alleged to be 
the implicated diameter, but, as I have asserted, at the fore part of the 
head somewhere near the coronal suture, then the burden of reconciling 
this fact to theory must rest on those who hold to the initial dip of the 
posterior fontanelle. 
Let me summon to the stand impartial witnesses, such as had no pet 
theories to which their facts were trimmed. And, in these forceps days, 
I own to some difficulty in finding cases of labor in narrow pelves which 
were either neglected, as we should now call it, or left entirely to the 
unaided efforts of nature. Nor are the following examples noting the 
pressure-mark, selected ones; but the only ones which I have been able 
to collect within a short and busy time. 
In describing a natural labor in a pelvis whose conjugate measured 
about three inches and a quarter, Mlle. Anna Puejac, midwife in chief 
of the Maternite at Montpellier, says1 that " At the anterior angle of the 
left parietal bone, there was a very considerable depression, sufficient to 
admit the half of an ordinary egg.' It was the exact cast of the promon- 
tory." Smellie writes2 that in a case of narrow pelvis he waited until 
the head was "squeezed down to the lower part of the pelvis"-that is, 
had passed the brim. The pains failing, he then applied the forceps 
along the sides of the pelvis, and caught the head, which was still trans- 
verse, over the face and occiput. "The child's head was squeezed into a 
longitudinal form, flattened on the sides, with a deep impression on the 
cranium above the ear." Again he tells us that, after a woman, who was 
"very much distorted," " had been in strong labor for four-and-twenty 
hours," he found " the head down to the lower part of the pelvis," viz., 
past the brim, and applied the forceps first over the face and the 
occiput, and then, when the perinaeum began to bulge, over the sides of 
the head. " The head was of a lengthened form, and contorted to one 
side, and there was a deep impression above the ear." 
Lachapelle contends, as the result of close observation, that "the head 
of the foetus, driven through a narrow and solid pelvis, is fractured and 
indented near one of the frontal bones. This accident is not uncommon, 
and we shall cite many examples of it."3 Again, she writes, "I have 
remarked with Smellie (tome ii. p. 533) that, in cases of natural labors 
in pelves considerably distorted, the depression is no longer found on the 
frontal region (sur le front), but near the temporal region."4 Out of a 
number of cases reported by her I select the following: Case I. Occiput 
1 Gazette Obstetricale, Juin 20, 1876, p. 179. 
2 Collection of Cases, 1778, Collection xxvii., No. 2, Cases iii. and iv. 
Eleventh Memoir, p. 423. 4 Ibid., p. 429. to the left; the anterior fontanelle was easier to reach than usual. A dead 
child was born naturally ; it had the frontal boss indented and broken.1 
In another case,2 the occiput was to the right; conjugate 3.25 English 
inches; a dead child was born naturally after a long labor. "The right 
frontal bone, although without fracture, offered a very marked depression 
which was undoubtedly due to the jutting promontory." In a third case 
the conjugate measured 3.25 English inches; position of the child's head 
not known ; after six and twenty hours of labor the forceps was applied 
along the sides of the pelvis; "extraction prompt and easy." The left 
frontal and parietal bones were found fractured.3 A fourth case4 was a 
primipara, with a conjugate of about 3.5 English inches, and with a 
second position of the vertex. The forceps was applied to the sides of 
the head, but failed to extract; the blades were, therefore, withdrawn 
and applied in each ilium. There was now no further delay in delivery. 
The child weighed five pounds,and died twelve hours after birth. "The 
right Jr was depressed and fractured by the sacral promontory." In 
a fifth case,5 the conjugate measured 3.25 English inches. The occiput 
looked to the left ilium ; the sagittal suture lay transversely and on the 
sacro-vertebral angle, with the right parietal affronting the inlet. 
Siebold describes a typical case of unaided labor in a pelvis of 3.5 
inches.6 At the first labor, a dead child was delivered by the forceps. 
At the second labor, the head presented transversely, with the occiput 
to the right ilium. By means of ergot a dead child was expelled. It 
had lesions and furrows at both temporal regions. At the third labor, 
the head presented transversely " with the small fontanelle to the left 
and the large to the right." " It was also greatly extended, to the right," 
viz., the forehead dipped. After many hours of hard labor, the head 
was driven past the promontory, and then the vertex rotated anteriorly 
to the first position. Thereafter the child was soon delivered. It 
weighed seven pounds, was dead, and had the left temple denuded of its 
cuticle, at a point on a level with the small anterior inferior fontanelle 
(Casserius's fontanelle). At the autopsy, four fissures were found ; one 
on the left side of the coronal suture (on the frontal bone), and three on 
the parietal bone. In the same journal, Carus reports an analogous case, 
in which there was a furrow of the parietal and a fracture of the frontal 
bone. Scholler, of Berlin,7 relates a unique case of labor in a primipara 
with a narrow pelvis. At the end of three days the woman was delivered 
of a living child. " In the middle of the left parietal, and in the neigh- 
borhood of the left temple, the skin was abraded and the bone depressed." 
" The bone beneath died, and a portion as large as a sixpence of the whole 
thickness of the parietal bone exfoliated, leaving the dura mater exposed. 
The destruction of the frontal bone was less considerable." The Transac- 
tions of the Medical Society of Erlangen contain the history of a case of 
spontaneous delivery in a narrow pelvis, reported by W. J. Schmidt.8 
The child was still; its skull had a fracture and a depression on the left 
frontal region. In the same paper analogous examples are given by II. A. 
Ilirt and Jorg. Another case of natural labor, in a pelvis measuring 
1 Fourth Memoir, p. 154. 
3 Eleventh Memoir, p. 475. 
5' Ibid., No. i. p. 463. 
6 Revue Medicale, 1833, tome i. p. 301; from Siebold's Journal fiir Geburtshiilfe, B. xi 
S. 404. 
7 Berlin. Medicinische Zeitung, September, 1841. 
8 Jorg, Schriften zur Kentniss des Weibes, Bd. ii. S. 123, 130. 
2 Eighth Memoir, p. 189. 
4 Ibid., p. 469. about three inches, is given by Osiander.1 After the most violent expul- 
sive pains a dead child, weighing six and a half pounds, was born, with 
fracture of the left parietal and frontal bones. Danyau, whose excellent 
paper2 has furnished me with some of these references, gives the following 
remarkable history of a woman whose pelvis was found after death to 
measure 2.75 French inches: Iler first child was delivered dead by the 
forceps. In five succeeding labors each child offered by the breech, and 
one was born alive. In her seventh and eighth labors the head presented, 
and the children were born without aid, but dead. In her ninth labor 
she was brought to the Maternite. The head came first, and for four 
hours stayed locked at the brim. Its sacral side was then felt suddenly 
to bend in, and the same pain drove it down to the vulva. The child 
was dead. Its skull had a deep depression overlapping the left coronal 
suture, and shelving obliquely backward to the boss. The death of the 
mother on the fourth day permitted a careful measurement of the pelvic 
diameters. 
Levret3 writes of a natural labor in a narrow pelvis in which the " face- 
half" of the head was obliquely furrowed. Antoine Luges contends,4 
that "The bones of the skull are often fractured with depression by the 
sacro-vertebral angle of the mother. It is one of the frontal, or, indeed, 
one of the temporal regions, which is the most ordinary site of these 
lesions." As a voucher for this statement, he gives an example of a 
living child born spontaneously, after a labor of thirty-six hours, through 
a pelvis measuring 3.25 English inches. The occiput presented to the 
right, and the right temple showed a red and contused furrow.5 In 
another case, the left frontal bone was so depressed as to push the corre- 
sponding eye nearly out of its socket. Velpeau declares,6 that " the 
depression of the parietal or of the frontal, with or without fracture, has 
been observed at the Maternite of Paris." Budin, a most careful observer, 
met with a case of spontaneous delivery in a fiat pelvis measuring about 
3.4 English inches in its conjugate.7 The occiput presented to the left, 
and a small living child was born twenty hours after the rupture of the 
membranes. On the left frontal region it had a deep furrow, which 
started from the coronal suture at the anterior fontanelle, and ran 
obliquely backward toward the base of the skull. Chailly-Honore holds8 
that " The depressions of the skull have their site ordinarily on the 
frontal or the parietal bones," and are often the result of natural labor 
in a reniform pelvis. Casper, after giving a list of writers on this subject, 
whose works are unfortunately beyond my reach, says that the skull- 
fractures caused by unaided labor are commonly on the parietal bone 
" and usually transversely to the sagittal suture." Sometimes they are 
found "stretching from the frontal bone more or less parallel to the sa- 
gittal suture."9 From these citations, it follows that the site of the bone- 
lesions caused by a natural head first labor in a fiat pelvis, is found, not 
at one of the poles of the biparietal diameter, but either directly over the 
' Handbuch der Entbindungskunst, Bd. ii. Abth. 2, S. 206. 
2 Journal de Chirurgie, par Malgaigne, Janvier, 1843, p. 42. 
3 Accouchements Laborieux, Paris, 1762, p. 119. 
4 Manuel d'Obstetrique, Montpellier, 1840, part v. sect. i. p. 306. 
5 Thfese, No. 64, 1821, pp. 51, 54. 
6 Accouchements, Paris, 1835, tome ii. p. 588. 
7 De la Tete du Foetus, Paris, 1876, p. 58. 
8 Accouchements, Paris, 1867, p. 950. 
9 Forensic Medicine, New Sydenham Society, vol. iii. p. 118. track of the coronal suture, or on either side of it, and generally parallel 
to it, and at right angles to the sagittal suture.1 
After turning in a flat pelvis, or in one narrowed mainly in its conju- 
gate diameter, a very analogous crania] mechanism takes place. The 
partial extension of the wedge-shaped head throws the biparietal diameter 
to one side of the promontory, and places in the conjugate of the brim 
the small bisauricular (bimastoid) diameter-viz., that portion of each 
temporal region lying directly in front of the ear. Now, upon traction, 
if the occipito-frontal diameter of the head be short, or the occipital 
portion of the pelvis roomy, the head will pass in the transverse (bis- 
iliac) diameter of the brim, and in a state midway between flexion and, 
extension, while the transit-furrow will be vertical, running directly 
upward from the smaller bisauricular diameter to the larger bitemporal 
diameter, close to and parallel to the coronal suture. If the head be 
large or the brim shortened in its transverse diameter, the resistance to 
the descent of the hind-head tends to bring about two movements; the 
one of flexion, and the other of occipito-frontal displacement towards the 
forehead side of the pelvis. The head should, therefore, pass in the 
resultant of these forces and of traction ; viz., in a line running some- 
what obliquely from the front of the ear, or from the anterior inferior 
angle of the parietal bone, to the vault posteriorly. But this transit-line 
is more vertical than in the given case of unaided head-first labor, being 
very generally found very near and almost parallel to the coronal suture, 
sometimes indeed in the very gutter of this suture-track. For the sacral 
side of the head being, under traction and propulsion, quickly bent in 
and fixed by the promontory, resists occipito-frontal displacement; while 
free lateral bulging at uncompressed points prevents any exaggerated 
lengthening out of the occipito-frontal diameter. Furthermore, supra- 
pubic propulsion together with two movements of unremitting traction, 
first in the axis of the outlet and then in that of the inlet, cants the base 
of the skull over the edge of the promontory, causes its sacral side to be 
nipped high up, and makes its pubic side revolve around the promontory 
as a centre of motion, and descend over the glib under-surface of the 
pubis; in other words the head is, as I have elsewhere expressed it, 
warped around the promontory.2 
Now, since this mechanism of a head-last labor in a narrow pelvis is 
yet mooted, I shall try to prove it by such clinical histories as note the 
site of the pressure-furrow. Smellie,3 after turning in a narrow pelvis, 
and making traction on the child's body " with all my strength," delivered 
a living child, which did well, although it had "a depression of the 
temporal bone before the ear, and the frontal and parietal bones pushed 
outwards." Madame Lachapelle4 advises turning in narrow pelves in 
1 In order to facilitate the work of others in this direction. I append the following refer- 
ences to papers on fractures of the foetal cranium, which 1 have not been able to consult: 
Proems verbal de la distribution des prix, June 20, p. 64, etseq.; London Medical and 
Surgical Journal, March, 1834, p. 145; Charles West, in Medico-Chirurgical Transactions, 
2d series, vol. x. 1845, p. 404; Siebold's Journal fiir Geburtshiilfe, 1825, B. v. S. 224, B. 
xi. S. 400; C. F. Hedinger, fiber die Knochenverletzungen bei Neugebornen in Med.- 
gericht llinsicht, Leipzig, 1833. The following authors have also written on the same 
subject: Chaussier, Meissner, Siegel, Ollivier, D'Angers, Viardel, Haller, Bose, Berchols, 
Deventer, Dionis, Roederer, Baudelocque, and Stein. 
2 Philadelphia Medical Times, March 20, 1875. p. 386. 
3 Cases in Midwifery, Collect, xxxiv., No. ii., Case ii., p. 237. 
4 Pratique des Accouchements, Paris, 1825, Eleventh Memoir, p. 429. LABOR IN NARROW PELVES. 
11 
order to make the head descend midway between flexion and extension, 
so as to get the " ternporo-auricular diameter" in the conjugate. From 
several cases of head-last labor in narrow pelves, which she narrates, I 
select the following: Case I.1 Primipara; conjugate 2.75 French inches; 
vertex presentation ; forceps slipped ; prolapse of the cord ; version ; head 
extracted with difficulty and with a sudden jerk (secousse brusque). A. 
large girl was born alive, but did not live long. The head had a deep de- 
pression on the left frontal bone. Case II.2 Second position of breech; con- 
jugate 2.5 French inches; child weighed five pounds and had been dead 
for some time. The head had "a deep depression of the right parietal in 
its anterior portion and near the temple, caused by the sacral promontory." 
Case III.3 First position of breech; "For more than ten minutes the 
head resisted the most violent tractions" (aux efforts les plus violens). 
Child did well for twenty-four hours and then died in convulsions, from 
the cranial lesions. An autopsy revealed the separation of the right 
parietal bone from the temporal along its whole inferior border. 
J. J. Phillips4 reports three cases of successful version in contracted 
pelves after failure with the forceps. In one of them the child had a 
" marked depression on the left parietal and frontal bones." Here the 
transit-line followed the course of the coronal suture. Carl Ruge5 gives 
six cases of fracture of the frontal bone, and one along the temporo- 
parietal suture, after version. In the seven of my own cases6 in which 
the pressure-furrow is noted, the site was near or on the coronal suture. 
The late Prof. E. Martin, of Berlin, says7 that, after version, "These 
impressions or depressions of the respective parietal bone are always to be 
found upon its anterior portion, more or less near the coronal suture." 
Dr. R. Barnes avers8 that "The mark of pressure or indentation against 
the jutting promontory is always seen at one end of this short diameter:" 
viz., the bitemporo-frontal. Dr. I. E. Taylor, of New York, in describing 
a case of labor in a pelvis measuring 2.5 inches in its conjugate diameter, 
states that " By version and propulsion from above the pubes, the head 
was flattened or indented at the junction of the parietal and frontal bones, 
which is the usual place."9 Many other examples could be cited, but 
further evidence is needless. 
From this mechanism it is clear that version closely imitates the pro- 
cesses of nature, for by it the head enters and passes the conjugate by 
its shortest diameter, where four yielding bones meet; where four wide 
sutures converge ; where the fontanelle is large and always open ; where 
overlapping is -most free, and where compressibility is greatest. Since 
the resistance is limited mainly to the margin of the brim, that once 
passed (and generally with a well-marked jerk), there is usually no fur- 
ther obstacle to the descent of the head. It is now brought into relation 
with new pelvic diameters, and the greater friction of the broader and 
harder surface of the hind-head brings about the needful movements of 
flexion and of rotation. To effect this the line of traction must be 
changed to that of Carus's curve, and finally to one at right angles to 
the mother's body. 
1 Op. cit., Eleventh Memoir, p. 481. 2 Ibid., p. 486. 
3 Ibid., Fourth Memoir, p. 157. 4 Lancet, March, 1871, p. 404. 
5 Bulletin General de Therap., Aoflt 15, 1875, p. 130. 
6 American Journal of Obstetrics, August, 1875, p. 197. 
7 Richmond and Louisville Medical Journal, April, 1870, p. 421. 
8 Obstetric Operations, London, 1871, chap, xvi., p. 237. 
9 Transactions of the New York Academy of Medicine, September, 1875. TfO'OTTrL, 
But there are mechanical advantages which turning possesses over a 
cephalic presentation in a narrow pelvis. Outside help, that of traction 
and of propulsion, can be invoked without in the slightest degree inter- 
fering with the natural mechanism. Again-and this must not be 
overlooked-by turning, the head enters the brim by the very short bis- 
auricular (bimastoid) diameter of its base, and passes the conjugate by 
the larger but more compressible bitemporal diameter of its vault; that 
is to say, the small end of the wedge is first nipped. In the correspond- 
ing head-first labor, the reverse to this takes place; for the head enters 
the conjugate by its bitemporal, or the vault portion of its bicoronal 
diameter. Brom repeated measurements taken shortly after birth, I find 
that the average length of the bisauricular diameter is 2.6 inches, and 
that of the bitemporal diameter 3 inches-a difference of nearly half an 
inch. 
From this description of the cranial movements, it follows that turning 
should be limited to cases of antero-posterior shortening of the brim. For, 
in other kinds of narrowing, the previously described mechanism, so essen- 
tial to success, could not take place. In the generally and uniformly nar- 
rowed pelvis, the transverse (bisiliac) diameter of the brim would probably 
be too short to permit the after-coming head to pass in a state midway 
between flexion and extension; while, on the other hand, if the head 
were forcibly flexed, a longer diameter than the bitemporal would be 
jammed into the short diameter of the brim. Again, from the narrow- 
ing of all the diameters of the whole pelvis-brim, bony canal, and out- 
let-the after-coming head would be detained at every stage of its 
descent, and could not, therefore, be delivered soon enough to avert 
fatal asphyxia. To save the life of the child, then, the forceps, and not 
turning, is here needed. As a corollary to this, less power and time are 
needed after version to deliver an average head in a flat pelvis, than a 
large head in an average pelvis ; for, in the former, the resistance is mar- 
ginal, and limited to a single osseous point; in the latter, diffused more 
or less, not only over the whole bony brim, but over the pelvic canal and 
outlet. 
How to tell a uniformly narrowed pelvis from one narrowed mainly 
in its short diameter, becomes, then,an important question. Apart from 
careful digital examinations, much may be learned from measuring the 
distance between the anterior-superior spinous processes and that between 
the crests of the ilia. In a standard pelvis these distances average re- 
spectively 25 cent. (9.8 inches) and 28 cent. (11 inches).1 But what should 
mostly be relied on is the position of the head. When conjugate narrow- 
ing alone exists, or when it preponderates, the occipito-frontal diameter 
lies parallel to the transverse diameter of the brim, with the anterior 
fontanelle low down. A head so situated implies conjugate narrowing 
and transverse amplitude of the brim. When the pelvis is uniformly 
narrowed, or when transverse (bisiliac) narrowing preponderates, the 
head will be found high up and very strongly flexed. This happens 
because the resistance at the brim is equal on all sides, and the shorter 
arm of the occipito-frontal lever must therefore descend. The sagittal 
suture, for the same reason as in a standard pelvis, will be found running 
more obliquely than transversely. Such cranial conditions show that 
the transverse diameter of the brim is too short to admit the occipito- 
1 Carl Martin, Monats. fur Geburtsk., Dec. 1867. LABOR IN NARROW PELVES. 
frontal diameter of the head, and that version is consequently inadmis- 
sible. 
Turn now to the mechanism of labor when the forceps is used at the 
brim of a flat pelvis. If the blades are applied to the fronto-occipital, or 
to the fronto-mastoid diameter, the head, which is lying midway between 
flexion and extension, is-unless firmly nipped in the conjugate-forcibly 
flexed, and either the biparietal diameter, or some diameter longer than 
the bitemporal, is made to enter the short diameter of the brim. Again, 
the fronto-occipital compression to which the head is subjected, not only 
prevents the natural lengthening out of the long diameters, but it causes 
bulffino- of all the cross diameters. This is, of course, a mechanical dis- 
advantage, one which increases the difficulty of the head's transit, and 
which can be overcome simply by a brute tractile force-such as puts 
foetal life in jeopardy. In addition, the fronto-mastoid application tends 
to force a premature anterior rotation of the hind-head. Also, the line 
of traction on the forceps-handles will invariably be at an angle to the 
axis of the superior strait, and the brunt of the traction is wasted on the 
pubis. Finally, such an application, by flexing the head or by shortening 
its fronto-occipital diameter, so widens the iliac spaces that prolapse of 
the cord is very liable to occur. "Statistics show that out of five appli- 
cations of the forceps above the superior strait, no fewer than two are 
complicated by a prolapse of the cord. I," continues Chailly-IIonor6, 
"have met with it in the ratio of twice in three cases."1 
On the other hand, when the blades are applied along the sides of a 
head at the brim of a narrow pelvis and lying in its transverse (bisiliac) 
diameter, flexion is inevitable.2 So essential, indeed, is this movement 
for the accurate adjustment of the blades, that some practitioners try 
1 Accouchements, 1867, p. 643. 
2 The statement often appears in foreign medical works, that this application is imprac- 
ticable whenever the head lies in the transverse diameter of the brim. This is a mistake; 
for, although the long curved forceps then becomes virtually a straight one in so far as the 
pelvic curve is concerned, this application can be very generally made with a properly con- 
structed instrument, provided the head be not locked. With the Hodge or the Davis for- 
ceps I have frequently made this application, and have repeatedly seen others make it. 
Hodge and Meigs, it is true, condemned it; but they denied, not its practicability but, its 
advisability. Baudelocque, Oapuron, and Gardien, warmly advocated it, and it is now the 
habitual practice of some of the best obstetricians of Philadelphia. It possesses the great 
merits of securing the firmest grip, of compressing the head in its least vulnerable diameter, 
and of lessening the pressure on the bladder. Since the mode of making this application is 
peculiar, a description of it may not come amiss. If the occiput look directly to the left 
ilium-and this is the most common cephalic position in the simple flat pelvis-the woman 
is turned over on her back, and her coccyx made to project over the edge of the bed. The 
right (female) branch is first introduced in the right side of the pelvis, with the convex sur- 
face of its blade looking obliquely to the sacrum. By a rapid downward sweep and a spiral 
twist of its handle, together with upward pressure on the convex edge of its blade by the 
fingers in the vagina, it is rotated very nearly half of a circle over the forehead to the side 
of the child's head under the pubis. The left (male) branch is now so held at its lower 
convex edge by the tips of the fingers of the right hand, that its handle hangs down. 
While held in this position, the blade is introduced, as far as it can be made to go, in the 
right side also of the pelvis, over the child's left temple but under the shank of the female 
blade. The right hand is next carried to the still pendent handle, which it raises, and upon 
which it makes upward pressure. This movement, combined with a guiding pressure from 
the fingers of the left hand in the vagina, makes the blade glide up over the sacral side of 
the head. When the branches are united, the lock should press firmly on the tuberosity of 
the left ischium. Should the occiput look to the right ilium, the same general rules are to 
be observed. But now both blades are to be introduced in the left side of the pelvis-the 
left (male) blade first, and under the pubis; the right (female) with its handle pendent. 
The lock should now press firmly on the tuberosity of the right ischium. first to flex the head, either by the hand, by the vectis, or by one blade 
of the forceps. In my own experience, however, the act of locking and 
that of grasping the handles, usually bring about the needful amount of 
flexion ; for success in such an application of the forceps presupposes a 
certain amount of mobility of the head, which insures its flexion. 
Hence the large biparietal diameter, or one of its congeners, must 
inevitably pass directly through the narrow conjugate. But, apart from 
its width, the hind-head is the least compressible portion of the cranium. 
The parietal bosses, being projections, as their name indicates, and being 
also the centres of ossification, are the most unyielding points of the vault. 
They are in fact eburnaceous when compared with other portions of the 
parietal bones. The posterior fontanelle is small, not open, and not infre- 
quently ossified. The sutures are narrow. Only three bones meet there, 
the occipital and the two parietals. But the occipital bone goes to form 
the hard cranial base, and is incompressible. The compressibility of the 
hind-head is therefore limited to the equitation of the parietal bones. 
But being shored up and buttressed by the unyielding occipital bone 
underneath them, they cannot readily overlap or bend in. lienee the 
tedious traction needed for forceps-deliveries, when compared with that 
required after turning. Transit-furrows are rare, but, when present, 
they run anteriorly from the boss either obliquely toward the cranial 
base, or parallel to the sagittal suture. In a recent case of forceps- 
delivery this was very strikingly shown. The diagonal conjugate, mea- 
sured by the rule and finger, gave a length of four inches. The sagittal 
suture ran transversely to the left ilium, with the large fontanelle dipping 
down so low as to make it almost the presenting part. The blades of the 
forceps were applied to the sides of the head, which flexed on bringing 
the handles together. After strong traction of about two hours' duration, 
made alternately by the attending physician and myself, the head was 
finally delivered. It was much flattened, and presented on its sacral side 
the well-marked furrow of a fracture running from the parietal bone 
obliquely to the mastoid process behind the ear. The child was still; the 
mother died four days afterwards from peritonitis, and I now regret not 
to have turned. Duges1 also describes such a fracture of the parietal boss 
in one of his forceps cases. Fractures and furrows at this site would far 
more frequently happen in instrumental labor, were it not that the hard 
boss so resists the direct pressure upon it as either to flatten the whole 
parietal bone, or to cause lesions of it at weaker, although unimplicated, 
points. 
But there are mechanical objections still stronger against the forceps 
when compared with version. The base of the skull being unyielding, 
the head cannot be compressed so readily by catching the vault with the 
forceps. For the effect is then to direct the compressive power toward 
the unyielding base. But by turning, the compressive power is directed 
toward the yielding vault. Further, from the peculiarity of construction 
of the forceps, the compression exerted by it is necessarily diffused over 
the whole surface covered by the blades. Now, in a bilateral application, 
the tips of the blades cover the bones of the cheeks, which are incompres- 
sible and so narrow as to need no compression whatever. Hence, not 
only is this amount of compressive power misapplied and sheer waste, 
but it detracts by so much from that applied to the offending diameter- 
the biparietal. Thus the surface covered by the blades not only involves 
1 Manuel d'ObstStrique; Montpellier, 1840, part v. sect. i. art. i. p. 306. 1J A D U n UN A K U W E L L V E 5 . 
unimplicated diameters, but it is too broad to be very materially reduced 
by compression. Even when the handles are lashed, but little more is 
gained, and that little at the expense of a prolonged, disorganizing pres- 
sure upon the brain. Baudelocque's exceptionally powerful forceps were, 
with lashed handles, found by their inventor barely to reduce the bi- 
parietal diameter as much as four lines, although the force applied was 
so great and so prolonged as to spoil the three instruments used. It fol- 
lows, therefore, that the Hodge or the Davis forceps, which are much fee- 
bler instruments than the French one, cannot compress the biparietal 
diameter as much as three lines, and the operator is therefore compelled 
in narrow pelves to make the anterior portion of the brim and the pro- 
montory of the sacrum do most of the compressing work; and that by 
sheer and prolonged dragging force, which, as in the case just narrated, 
threatens injury to the mother and death to the child. 
Again, the forceps-blades being of equal length and breadth, and being 
also applied to corresponding surfaces of the child's head, make equal 
compression upon the pubic and the sacral side of the head. But from 
the limitation of the bone-lesion in these pelves to the posterior half of 
the brim, the pubic side of the head needs no compression ; for its con- 
vexity naturally adapts itself to the smooth concavity of the anterior half 
of the brim. Therefore just one-half of the effective compressive power 
is absolutely thrown away. For granting that, in a given case of conju- 
gate narrowing, the forceps reduces the biparietal diameter by three lines, 
this diminution does not facilitate to the same extent the passage of the 
head ; for supposing that it actually reduces the width of the head by 
three lines, yet it does not virtually so reduce it. This is evident from 
the fact that the pubic side of the head needs, not compression, but adap- 
tation, and the bulging tissues around the periphery of the blades will 
at points separated by their width still impinge on the pubic concavity 
of the brim, making the clamped portion of the head subtend the sym- 
physis pubis like the chord of an arc. In all the narrow pelves belong- 
ing to the museum of the Philadelphia Obstetrical Society, and one of 
them is under two inches in its conjugate diameter, the pubic side is con- 
cave and smooth. After a careful examination of the distorted pelves in 
the museum of the University of Pennsylvania, I find that the same con- 
dition obtains in all that were not affected by osteomalacia. Turn now 
to the sacral blade of the forceps ; it is the posterior half of the brim 
which is distorted; and to its irregular configuration must the sacral side 
alone of the head be moulded. Since also the distortion is mainly owing 
to the descent of the sacrum as a whole, and to the anterior projection 
of its promontory, the portion of the head needing moulding is a small 
area of surface corresponding with the sacro-vertebral angle. In other 
words, it is, when flexion is forced by the forceps, the biparietal dia- 
meter alone that needs shortening, and that by the indentation of its 
sacral pole. But the very width and length of the sacral blade thwarts 
this indication. This blade flattens the whole sacral surface of the head, 
but does not mould it. The whole head and included brain are in fact 
flattened out by the two blades. And this excessive bilateral compression 
so unnecessarily lengthens out all the other diameters of the head, that 
every physician has seen forehead bulging out, eyeballs starting from 
their sockets, and life destroyed by the violent and prolonged compression 
to which the whole brain has been subjected. In one word, by the bi- 
lateral compression of the forceps the pubic blade interferes with the pro- 
cess of adaptation ; the sacral blade prevents the utilization of the roomy concavities on each side of the promontory, and the whole brain is, there- 
fore, subjected to an unnecessary amount of compression. 
The catch-word " moulding," which is so much used to designate the 
action of the forceps, is a misnomer. Moulding here means an outline 
conformity of the cranium to the kidney-shaped configuration of the 
brim. To attain this end, it is needful for the pubic side of the head to 
adapt itself to the smooth concavity of that portion of the pelvis, for 
the occipito-frontal diameter to be moderately lengthened out, for a 
limited area of the sacral side of the head to be bent in by the promon- 
tory, and for lateral bulging to take place around it in the very roomy 
sacro-iliac spaces. No moulding of the head, in its true obstetric sense, 
can possibly occur, unless, as in natural labors or by version, the pelvis 
itself acts the part of the moulder. Look at a head in the grasp of the 
forceps applied bilaterally. How is it possible for this steel-ribbed head 
to alter its shape to that of the brim? How can any bending-in take 
place within the fenestra of the sacral blade, whose iron rim, by firm 
pressure, acts as an abutment to the included parietal boss? How can 
the pubic side of the head adapt itself to the anterior portion of the pel- 
vis? How can the head bulge out at points clamped by iron ? The 
forceps, thus applied, indeed moulds the head, but to its own shape, and 
not to that of the brim. For how can bow-shaped blades mould a head 
to a kidney-shaped brim? The thing is an impossibility. Who ever 
saw a head kidney-shaped which had been delivered in such a manner 
through a narrow brim? The truth is that the head then passes the 
brim by being flattened out, and not by being moulded ; and, what is 
worse, since the blades do not exert the needful compressive power, the 
promontory itself is made to do most of this unnatural work-the work 
of flattening and not of moulding. When the head is squeezed suffi- 
ciently flat, it is delivered by being dragged straight past the promon- 
tory, without revolving around it as it does in natural or in version 
cases. 
So true is this that, when a head has been delivered through a small 
conjugate by the forceps applied bilaterally, never will it exhibit a cast 
of the promontory by a spoon-shaped depression, and only once have I seen 
a slight furrow. The whole head is flattened, the bones are separated at 
the sutures, sometimes so much so as to seem loose in a scalp-bag, but no 
lesion of limited area is found by a surface examination. Post-mortem 
examination will, however, reveal fissures and fractures radiating from 
the base of the parietal boss. 
It follows that the hackneyed term of " wire-drawing" the head by 
the forceps, is also a misnomer. In " wire-drawing," the pincers which 
seize the end of the wire do not pass through the graduated holes in the 
draw-plate, but work outside of them. But when the head is seized by 
the forceps, the pincers, so to speak, must also pass through the bony 
draw-plate itself. So great a disadvantage is this, that there are on 
record far more remarkable cases of successful natural delivery in very 
small pelves, than there are by this use of the forceps. For it stands to 
reason that when a forceps, whose blades lie from two and three-quarters 
to three inches apart, is applied to the sides of a head at the brim of a 
pelvis with a conjugate of less width, the blades will need wire-drawing 
as much as the head, before they can be made to pass. 
So far the use of the forceps. Mark now what happens when the 
child is turned in a flat pelvis. The wedge-shaped and semiflexed head 
enters the conjugate by its small bisauricular diameter, and passes it by its very compressible bitemporal diameter. The very cause of the conju- 
gate deficiency-the jutting promontory-becomes itself the moulder, 
and the plastic head, unhampered, unclamped, unribbed by bars of steel, 
being also drawn upon by outside traction, accurately moulds itself to the 
shape of this small bony barrier. Meantime the pubic side of the head, 
already presenting its convexity to a concavity, is made by lateral pres- 
sure to fit snugly the anterior half of the brim. Bulging takes place at 
all the uncompressed points, and the whole head becomes concavo- 
convex, being rapidly moulded to the kidney-shaped configuration of 
the whole brim, while backward traction and supra-pubic propulsion 
cause the pubic side to revolve around the promontory as a centre of 
motion. To my mind nothing can be plainer. How, otherwise, is the 
absence of vesical disturbance, after version, explainable? How the fact 
that, as I have seen and others attest, it will take as many minutes, less 
minutes indeed, to deliver the head by version, as it has taken hours of 
unsuccessful traction with the forceps? Even without these facts and 
without a cloud of witnesses to sustain them, an d priori reasoning would 
compel me logically to the inevitable conclusion that version possesses 
great mechanical advantages over the forceps. 
One word in regard to the obliquely ovate pelvis. If the hind-head 
present in the less roomy side, by turning, the soft and voluminous breech 
is very likely to adapt itself and pass through the more roomy side. This 
tendency, together with a knowledge of the fact that the foot drawn on 
usually rotates to the pubic arch, ought, very generally, to enable the 
practitioner to place the occiput in the larger half. Yet so great an 
advantage is it to turn, that Barnes and Strassmann declare1 that they 
have saved the children, even when they had failed by this operation to 
effect the desired change of position. 
The use of the vectis, or tractor, in narrow pelves has been so highly 
lauded by Boddaert, of Brussels, Raffaele, of Naples, Fabbri, of Bologna, 
Marchant, Herbiniaux, Coppee, Beytter, Frayes, and other Dutch, Bel- 
gian, and Italian writers,2 that a few words in regard to the action of 
this instrument are needed. 
When the head is transverse, this instrument should be passed over the 
pubic mastoid region ; when oblique and anterior, over the pubic side of 
the occiput ; and when oblique and posterior, over the pubic fronto- 
temporal region. At first it is used as a lever of the "first kind," the 
left hand on the shank representing the fulcrum, and the right hand be- 
coming the power by raising the handle toward the pubes. In other 
words, each hand acts in opposite directions-the left one mainly to pro- 
tect the pubis from pressure. As soon as the handle is raised high enough 
for the blade to secure a good hold, the right band is kept at rest to be- 
come the fulcrum of a lever of the "third kind," while the left acts as 
the power. This compound action of traction and leverage, peculiar 
alone to the vectis, here meets several important indications. As a lever, 
this instrument compresses the head from before backward in its lateral 
diameter, and aids the moulding of its free sacral surface to the posterior 
distortion of the brim. By its action as a tractor, it hooks down the 
pubic side of the head, making it revolve around the promontory of the 
sacrum as a centre of motion, and roll over into the pelvic cavity. 
1 Obstetric Operations; by R. Barnes, 1871, chapter xvi. p. 241. 
2 Cazeaux, edited by Tarnier, 1874, p. 998; Co.ngres Medical de France, 1865, pp. 584, 
589; Traite des Accouch., par Hyernaux; Bruxelles, 1866, p. 699; New Sydenham So- 
ciety's Biennial Retrospect, 1869-1870. p. 409. 
2 tfucruiLn, ladvk ixakkvw i blv as,' 
From the close resemblance of this mechanism to that of an unaided 
head-first labor, and to that of an aided head-last labor, I am led to think 
that the vectis, in skilled hands, will be found more efficient than the 
forceps in dislodging a head from the brim of a pelvis narrowed mainly 
in its conjugate diameter. Below the brim, and in the generally narrowed 
pelvis, it cannot of course compete with the forceps excepting in certain 
anomalous positions and presentations. But in selected cases this neglected 
single-bladed instrument is, in my opinion, destined to take rank over its 
double-bladed fellow. For instance, in 1863, the late lamented Fabbri, 
of the University of Bologna, quickly delivered with the vectis, through 
an artificial pelvis, a head which S. Tarnier,1 although using all his 
strength, was not able to budge with the forceps. The head was then 
replaced, and the forceps re-applied, but with the same want of success. 
Professor Tarnier, who is the narrator, then resorted to the lever, and, 
much to his surprise, delivered the head " with astonishing ease" {aver, 
une etonnante fadlite}. This experiment was repeated, and invariably 
with the same result. 
To sum up then the mechanism of natural and of artificial labor in a 
flat pelvis:-Nature makes the first-coming and the after-coming head 
enter the brim by extension ; the forceps by flexion. With the former 
the head engages in the short conjugate by its shortest and most com- 
pressible diameter ; with the latter by its largest and most unyielding 
diameter. By nature and by version the head revolves around the pro- 
montory as a centre of motion ; by the forceps it is dragged straight 
past, over this osseous point. By the former the head is moulded to the 
outline configuration of the brim ; by the latter, when applied to the 
biparietal diameter, it is moulded more to the shape of the blades than 
to that of the brim. By the one the brain lesion is local and limited to 
the area bent in by the promontory ; by the other the area of undue com- 
pression is increased. By nature and by version the compression is that 
which is needed and no more; by the forceps it is more than is needed. 
Regarding then alone the mechanism of labor in narrow pelves, to 
which the scope of this paper is strictly limited, the following conclu- 
sions are reached:- 
I. The unaided first-coming head and the aided after-coming head 
observe in a flat pelvis precisely the same general laws of engagement 
and of descent. Hence, version here means art plus nature. 
II. The forceps, however applied in a flat pelvis, antagonizes more or 
less with the natural mechanism of labor. Hence, the forceps here means 
art versus nature. 
III. The aided and the unaided first-coming head observe in a uni- 
formly narrowed pelvis precisely the same laws of engagement and of 
descent. But version violates these laws. Hence, the forceps here 
means art plus nature ; version, art versus nature. 
IV. At or above the brim of a flat pelvis, the fronto-mastoid or even 
the fronto-occipital application of the forceps interferes less with the 
moulding of the head, and violates less the natural mechanism of labor, 
than the biparietal application. 
V. In the flat pelvis, the vectis aids the natural mechanism of labor, 
and, therefore, meets the indications better than the forceps. 
1 Cazeaux's Obstetrics, 1874, p. 996.