ON  THE  FUNCTION

                          OF THE


MALPIGHIAN  BODIES  OF THE  KIDNEY.
                              V
                    By 0. E. Isaacs, M.D.,

       DEMONSTRATOR OF ANATOMY IN THE UNIVERSITY OF NEW YORK.

                    READ FEBRUARY 4, 1857.
     In March last I read a paper before the Academy of Medi-
  cine upon the Structure and Functions of the Kidney.   It may,
  perhaps, be remembered, that at that time I took occasion  to
  dissent from the  opinions of Mr. Bowman (whose views have
  been so  generally adopted by the profession), not only with
  respect  to the nature of the  venous  plexus, &c, but  also
  in regard to the structure and function of the Malpighian coil
  or tuft.   I then concluded, that instead of merely " separating
  water from the blood, while the  urea, lithic acid, salts, &c,
  are separated by the epithelial  lining of the  uriniferous tubes
  from the blood of the venous plexus, which surrounds them "
  these tufts, on the contrary, were actively engaged in secreting
,  several of the proximate  elements of the urine.  This view was
  deduced from the following facts:
     1. That the urea, lithic acid, and salts of the urine have been
  found to exist in the blood of healthy animals.  That in various
  diseases, and especially after extirpation of the kidneys these
  substances are found, in  large proportion, in  the  blood.  It is,
  then, proved that they pre-exist in the blood, and are merely
  separated from it in the kidney.
     2. The renal  artery which supplies the kidney must neces- 
438
On the  Function of the
 sarily contain these proximate elements of the urine, and as the
 Malpighian tufts are placed upon the terminal twigs of this
 artery^they must consequently enter the tuft.  A glance at the
 structure will lead inevitably to this conclusion.
    3.  Most diuretics enter the circulation and can be detected
 in the urine.  They can arrive at the kidney only through the
 renal artery, and consequently  must enter the Malpighian tuft.
 It would be too tedious and unnecessary to mention the various
 substances which, after having been  absorbed, and having
 entered the circulation, have been found in the urine.  I will
 only refer to  a few which have been given  by authorities:
 salts of iodine, bromine, sulphur, arsenic, antimony, mercury,
 copper, silver, lead, iron, mineral and organic  acids and their
 salts, as the acetates, citrates, tartrates, &c, &c.; the  balsams,
 cubebs, garlic, turpentine, asparagus,  &c.;  ajso quinine and
 morphine, &c, &c.   Urea, when given internally, acts as a
powerful diuretic.
   4. According to Mr. Bowman, the Malpighian coil or tuft
 lies naked in the capsule of the uriniferous  tube ;  which  is a
 proof that it does not separate the complex proximate elements
 of the urine from the blood, but  merely water, the coil or tuft
 being, as he  says,  " a bare or naked  system of capillaries."
 Now I have  conclusively demonstrated, by various processes,
 that the Malpighian tuft or coil is covered  by oval, nucleated
 cells, which are differently affected by chemical reagents from
 those which line the capsule, and consequently have a  different
 organization.  The Malpighian tuft is evidently, then,  a gland-
 ular structure, every way  adapted for  the separation of the
 proximate elements of the urine.
   5. In  opposition  to the view that the Malpighian tuft  is
 merely for the separation of water from the blood, it may be
 stated, that in serpents,  alligators, turtles, &c, the Malpighian
 bodies abound throughout the cortical substance, and in some
 of these animals, throughout the whole structure of the kidney,
 yet their urine is secreted in the semi-solid state.  It is not easy
 to reconcile this view with the theory that the Malpighian tuft
 merely separates water from the blood.
   6. In  the kidney of a patient who had been jaundiced for 
Malpighian Bodies of the Kidney.         439
several years I ascertained the presence of the coloring matter
of the bile in the capsule of the Malpighian tuft, and in  the
commencement of the uriniferous tube.  By the application of
a drop of nitric acid, the Malpighian bodies exhibited the usual
changes of color which are seen when this acid is brought in
contact with bile.  I therefore concluded, that in this case  the
coloring  matter  had been separated by the Malpighian tuft,
passed into the  capsule, and  downwards into the uriniferous
tube.
   7. Within the last three months, I have performed several
experiments upon animals by introducing into the stomach and
intestines various coloring matters, capable  of being absorbed,
entering the circulation, and passing into  the kidney.   My
object was to ascertain whether they would  be detected in the
uriniferous tubes alone, in which case it might be supposed
that they were separated by the epithelial  cells of the tubes
from the blood of the venous plexus, as believed by Mr. Bow-
man ; or whether they would be found in the Malpighian body
as well as in the tubes, when there would seem to be no doubt
that the Malpighian tuft separated the coloring matter,  which
had then passed into the capsule, and so on  into the uriniferous
tubes.  Being very anxious then to ascertain what parts of the
minute structure of the kidney would be found to be engaged
in this process of separation or secretion, I performed the fol-
lowing experiments.   In  all  of  them the  animals were  put
under the influence of sulphuric ether, so as to produce insen-
sibility during the operation:
   No. 1.  I opened the abdomen of a dog,  and tied both ure-
ters ; a ligature was then placed on the ileum, near its entrance
into the c<ecum.   A small opening was made into the duode-
num, about six inches from the stomach, and two ounces of a
mixture  of finely pulverized  indigo and water were  injected
into the stomach.  The tube of the syringe being again placed
in the same opening, four ounces of the mixture were  injected
downwards into the jejunum and ileum.  Ligatures  were placed
on the intestine, above and below the opening, in order to pre-
vent the escape of the injected fluid.   The abdomen was then
closed by the glover's suture.  This animal lived  twenty-eight 
440               On the Function of the
 hours after the operation, and died with the usual symptoms of
 poisoning,  by retention of the urea.  On post-mortem, there
 was  very little peritonitis.   On  making thin sections of the
 kidney, the Malpighian bodies and uriniferous tubes were found
 very much darkened by the indigo.  Both the bodies and the
 tubes were of various  shades of dark  blue  and  black, some
 being much darker than others.
    No. 2. I operated upon a cat in a similar manner, using
 however  a solution of deoxidized indigo, prepared according to
 the process of "the dyers, with  sulphate of iron and lime-water.
 By this process the indigo becomes very soluble, and of a light
 yellow color, absorbing oxygen, and turning  blue on exposure
 to  the air.  On dissection, not a trace of indigo could be found
 in  the kidney.  I do not know to what cause the failure of this
 experiment should be attributed.
    No. 3. I repeated the operation upon a small white dog of
 feeble constitution.   This animal  only  lived  fourteen hours.
 No indigo could be detected in the kidney.  I think the cause
 of  failure in this  case was owing to the fact  that the solution
 was made with cold, instead  of warm water, which should
 always be used, and also to too long exposure of  the intestines
 to the air.
    No. 4. I injected the mixture  of indigo and water into the
 stomach and intestines of a very large and ferocious black cat.
 The ureters were tied.   He lived thirty-four hours.  There was
 scarcely any peritonitis.   Both the  Malpighian  bodies  and
 uriniferous tubes were of a  light blue, and some of a very dark
 color.
    No. 5.  I repeated the  same operation on a  kitten, which
 lived  fifteen hours.  The Malpighian bodies and tubes were of
 very dark color, as in the preceding experiment.
    No. 6.  In a large grey cat I removed the left kidney, and tied
 the right ureter, hoping  that the remaining  kidney, by receiv-
 ing more  indigo, would show the Malpighian  bodies and  the
 tubes  more deeply  colored.    This  cat lived twenty hours
 Scarcely any peritonitis.  The Malpighian bodies and urinifer-
 ous tubes  were much darker than those of the animals of the
preceding experiment.   Rome of them were nearly as black as 
            Malpighian Bodies of the Kidney.         441

ink.   It is from a thin section of the kidney of this cat, under
the microscope, that the drawing and diagram have been made
by  my friend Mr. Benj. Howard,  an excellent artist, and a
student of medicine in the University of this city.






                          Plate 47.

    No. 7.  On the 28th of January I injected six ounces of a
 mixture of finely pulverized indigo and water into the oesopha-
 gus of a small dog.  Eighteen hours after,  I again injected six
 ounces more.   Twenty-four hours afterwards, I injected six
 ounces of the mixture.  Twenty-one hours after, four ounces
 were injected;  and three hours after this last injection, the
 animal was killed.  I may here mention that a brass pipe with
 a stop-cock had been left in the oesophagus, and secured in it
 by a ligature, so that the successive injections were made with
 great ease  and  convenience.  On examination,  only a small
 number of the  tubes and Malpighian  bodies were colored.
 Some of the last were of a light green color, others were
 slightly darkened;  a few  were more deeply colored.   The
 tubes were generally uncolored, except here and there in the
 pyramidal  portion of the kidney,  where some of the straight
 tubes were nearly black.  I regret that I  could not inject the
 indigo in this animal at such times as I  could have wished;
 could I have done so,  the result would probably have been
 more satisfactory.   It will thus  be seen that out of seven
 experiments with indigo, five succeeded, the Malpighian bodies
 and uriniferous tubes being both colored by it.  Berzelius found
 in indigo a brown, red, and  blue pigment.  This  fact may
 explain the shades of color which were seen in the Malpighian
 bodies and uriniferous tubes.   These organs may perhaps also
 produce some slight change in the coloring matter in its passage
 through them.  In  some thin sections of the kidney, the Mai- 
442
On the Function of the
 pighian tuft and capsule seemed to be filled with colored mate-
 rial, which could be traced along the tube, gradually becoming
 lighter in its progress  downwards.   In some of these animals
 the urine in the ureters, above the ligatures, was of a slightly
 blue color.
    No. 8. On the same day I injected a solution of the ferro-
 cyanide of potassium into the stomach and duodenum of a large
 cat, and then placed a ligature above the opening which had
 been made into the intestine  in order  to inject the  solution.
 About ten inches below this point I made  another opening into
 the intestine, and injected  downwards  into  the jejunum and
 ileum a weak solution of sulphate of iron. A ligature was placed
 just below this  opening, so  that the contents of the  intestine
 could not escape.  The two solutions were thus separated from
 each other by ten inches of intestine which contained none  of
 the solution.   Ligatures had previously  been placed on the
 ureters.  This experiment was performed at 3 p.m. on Saturday,
 and the animal was found dead on Monday morning, so that it
 is not known how long she lived after the operation.  The
 Malpighian bodies  and uriniferous tubes were of a dark blue
 color, showing that Prussian blue  had  been formed in the
 course of the circulation, and had passed through the  Mal-
 pighian bodies and  uriniferous tubes.  The urine was  of a
 slightly blue color.
    No. 9. I may also state that I have injected a mixture  of
 Prussian blue and water into  the stomach and intestines of a
 cat, and have found the Malpighian bodies and tubes of a dark
 blue color; but I regret to say that I  have  lost the notes of the
 experiment, although the specimen of the kidney is still in my
possession.
   No. 10. December  24, at  4 p.m., I tied the ureters  of  a
small dog and injected a solution of madder into the stomach
and intestines.  This dog was found  dead on the 26th.  The
Malpighian  bodies were of a brilliant red color, exhibiting  a
most beautiful appearance.   The tubes were dark red  and
some of them very darkly colored.  Thin sections of the kidney
were placed under the microscope, and  then touched with  a
drop of solution of caustic soda or ammonia, when the Mai- 
Malpighian Bodies of the Kidney.
443
pighian bodies and tubes became of a still more brilliant red
color.   The urine which was retained in the ureters, above
the ligature, was  acted on  similarly  by the same chemical
reagents.
   No. 11.  On the 22d of January, at 2 p.m., I injected a solu-
tion  of madder, containing a small quantity  of bi-carb. soda,
into the stomach and intestines of a dog.  This animal died at
8£ p.m. the same day.  The ureters had been  tied.  The Mal-
pighian bodies were of a bright red color.  Some of the tubes
were  simply darkened, others of a dark red color.  The fluid
in the ureters, above the ligatures, was reddened on the appli-
cation of carbonate of soda, and also of aqua ammonise.
   No. 12.  I injected a solution of the Brazil wood, Ccesalpinia
Crista, into the  stomach and intestines of a dog, having pre-
viously tied the ureters.  On examination, sixteen hours after
the operation, the Malpighian bodies were of a bright red color;
the tubes were darkened.   The red coloring  matter of Brazil
wood is very sensible to  the action of alkalies, and on touching
thin sections of the kidney, under the microscope, with solution
of ammonia or soda, the Malpighian bodies became of a purple
color.   The tubes exhibited this change only in a slight degree,
and many of them not at all.
   No. 13.  On the 24th of December last, at 12 m., I tied the
ureters of a large dog, and injected a solution of cochineal into
the stomach and intestines.  He was seen alive at 5 p.m., and
found dead on  the morning of the 26th.  The Malpighian
bodies were very red; some of the tubes dark red, and a few
of them were nearly black.
   No. 14.  On  the same day, at 3 p.m., I tied the ureters in a
cat, and injected a mixture of carmine  and water into the sto-
mach and intestines.  She was seen alive at five p.m., found
dead on the 26th.   The  appearance of  the Malpighian bodies
and the tubes was the same as in the preceding experiment.
   No. 15.  I injected into the oesophagus of a dog twelve ounces
of a mixture made by rubbing in a mortar two drachms  of
powdered cochineal with half a drachm of bi-carbonate of soda,
to which  one ounce of  glycerine was  added, and afterwards
eleven ounces of water.  At the end of three hours the animal 
444              On the Function of the

was  killed.  The appearance of thin  sections^ of the kidney,
under the microscope,  was exceedingly beautiful.   The  Mal-
pighian bodies were distended, and of a purple and purplish red
color.  Some of the tubes were light red, others were uncolored.
On adding a drop of solution of ammonia, the color of all these
parts was changed to a deep red.
   No. 16. I injected into the oesophagus of a cat three ounces
of a  similar mixture of cochineal and  three ounces of infusion
of madder.  At  the end of three hours this cat was also killed.
The Malpighian bodies and the tubes were of similar, but not as
deep  color as those of the dog in the last experiment.  The
same effect was produced  on thin sections of the kidney by
using ammonia as in the last experiment.
   No. 17. January 20th, at 3 p.m., I tied  the ureters of a cat,
and injected a solution of logwood  into the stomach and intes-
tines, having previously fixed a ligature on the  upper part of
the rectum.   This cat was seen living  at 9 p.m., and was found
dead  the  next morning.  There was no peritonitis, no sign of
inflammation or  congestion, except at one point, just below the
ligature,  on the  rectum.   Thin  sections of the kidney showed
the Malpighian bodies of a very red color.  Under the micro-
scope both these bodies and  the tubes were darkened by the
solution of the sulphate  of iron.   The urine retained in the
ureters and in the pelvis of the kidney was also  slightly dark-
ened by the same reagent.
   No. 18. On the 30th of January, at 1^  p.m., I  placed a liga-
ture  on the duodenum of a cat, and another about  the middle
of the jejunum.  Into this portion of included intestine I threw
a solution of  logwood.   An opening was then made below the
lowermost ligature, and a weak solution of sulphate of iron was
injected, a ligature having been placed on the ileum just above
the ileocecal valve.   This cat died  at 8 p.m. the same day.
The  Malpighian bodies were dark red, and much distended •
the tubes of a very slightly blue color.  Neither  were affected
by dropping upon them the solution of sulphate  of iron.  This
experiment was  unsatisfactory, and the cause of  failure is per-
haps to be attributed to the  fact that too large a  quantity of
the solution was injected, and the intestines consequently be- 
Malpighian Bodies of the Kidney.         445
came over distended.  Absorption, therefore, did not fully take
place.
   No.  19.  On the 2d February,  at  6 p.m.,  I injected six
ounces of a mixture of finely pulverized turmeric and water
into the oesophagus of a cat.  I repeated this injection several
times, and  on the 4th, at 4 p.m., she was killed.   I could not
detect the slightest trace of this coloring matter either in the
kidney or the urine, nor even-by chemical tests.
   No.  20.  On the 4th day of February I injected several
times into the oesophagus of a cat an infusion of logwood, mad-
der,  and Brazil-wood.   Four hours after she was killed.  The
Malpighian bodies were of a faint purplish red.  On applying
ammonia to thin sections, under  the microscope, the color was
increased.   The bladder was full of a pink-colored urine, which
was strongly reddened by ammonia, and also by caustic soda.
   No.  21.  I procured some of the Persian berries, or berries
of Avignon, which are much used by the dyers in coloring
cloths of a yellow color.  In experimenting with this substance,
I found that it contained a yellow coloring matter similar  to
that of  the bile, inasmuch  as when acted on by nitric acid  it
showed a play of colors similar to that which is exhibited when
bile is treated with the  same reagent.   I also ascertained that
the yellow coloring matter of Spanish saffron showed a transi-
ent green color when acted  on by nitric acid.   I injected an
infusion of equal parts of Spanish saffron and the Persian ber-
ries into the oesophagus of a dog, to the amount of eight ouw.es,
and  repeated this injection every hour  for four hours, at the
end of which time the dog was killed.  The Malpighian bodies
and  uriniferous tubes were of a yellow  color.   On adding a
minute quantity of dilute nitric acid to thin slices of the kidney,
under the microscope, a play of  colors was seen similar to that
which was  observed when some of the mixed infusion of the
Persian berry and  saffron was poured on  a  white plate, then
allowed to run  off by inverting it, and finally a drop of nitric
acid suffered to fall upon the plate,  when the rapidly changing
colors were  instantly perceived.
   If we now review the result  of the experiments up to this
point, it will be seen that of the various coloring matters which 
446              On the  Function of the
have been detected, both in the Malpighian bodies and in the
uriniferous tubes, by means of the microscope and by chemical
tests, indigo has been found five times, madder twice, cochineal
twice, and Prussian blue also twice.   Carmine, the mixture of
Persian berry and saffron, logwood and Brazil,  have  each  only
once been tried; and have  all been  detected in the kidney, as
has also been the mixture of logwood, Brazil-wood, and madder,
and likewise a mixture of madder and cochineal.
   I may here state, that in none  of my experiments with
coloring matters  have  I ever detected them in the venous
plexus of the kidney.
   No.  22. On  the 20th of December last I injected the sto-
mach and intestines of a cat with  a mixture of animal charcoal
and water, having previously ligated the ureters.  The animal
lived twenty hours.  Both the Malpighian bodies and the uri-
niferous tubes were of a very dark color, many of them being
intensely black.
   No 23.  At U p.m.,  on  the 2d of February, I injected six
ounces of a mixture of lampblack and water through  the oeso-
phagus  of a  cat.   At 10p.m. I repeated the process; also  at
1 p.m. next day, and again at 3 p.m.  The animal was killed two
hours after.   The Malpighian bodies and uriniferous tubes
were of various  shades of  blackness,  some  being  intensely
black.
   No.  24. At about 4 p.m. on the 2d of February, I injected
the (esophagus of a cat with a mixture of animal  charcoal and
water, to the amount of about eight ounces.  By mistake the
animal was killed about an hour  afterwards.  The uriniferous
tubes throughout  the kidney were very dark, some  of them
intensely black.   Many of the Malpighian  bodies were dark-
ened, but generally were not so much so as the  tubes.
   Nos. 25 and 26.  On the  3d of February, I operated upon
two cats, injecting the oesophagus of both animals with a mix-
ture of  animal charcoal and water, repeating the injection
several  times at  intervals until they were killed, which  was
about three hours after the operation.  In both of these  cats
the Malpighian bodies  and  uriniferous tubes were  of various
shades of blackness, some of them being intensely black. 
Malpighian Bodies of the Kidney.
447
   I should have previously remarked, that in some Malpighian
bodies the various coloring substances were sometimes seen in
the centre of the capsule, while a clear interval existed between
the colored portion and the inner surface of the capsule;  thus
showing that the coloring matter had not yet left the tuft.   In
other instances  the central portion  corresponding to the tuft
was only slightly colored, while a deeply colored part was situ-
ated between the tuft and the internal surface of the capsule.
   I think  these experiments  conclusively show  that the Mal-
pighian tuft can and does separate  coloring matters from the
blood which have been absorbed from  the stomach and intestines,
and have thus entered the circulation.
   No. 27.  On the 19th of January  I tied the ductus commu-
nis choledochus, or  common bile-duct, of a large grey cat, with
the view of allowing the elements of the bile to remain in the
circulation,  and the absorption of any which might have been
already secreted.   I hoped thus  to  be  able to detect it either
in the tubes or the  Malpighian bodies of the kidney.  This cat
lived  seventy-five hours, and  seemed to suffer but little from
the operation.   On taking off the skin, I observed the under
surface of it, in  several points, to be of a bright yellow color.
The  bile-duct was  partially ulcerated, so as  to allow of the
escape of a few drops of bile.   There  was very slight peritonitis.
Thin sections of the kidney exhibited the Malpighian bodies of
a light yellow color.  Nothing remarkable was observed in the
tubes.   On  adding a portion  of  a drop of nitric acid to  the
specimen under the microscope, the  Malpighian bodies showed
a  slight play of colors, among which  blue, green, and violet
could be most distinctly seen.  The same effect was seen in the
tubes, but not so clearly.  It was observed also on testing the
urine.   There could then be little doubt of the presence of bile
in the Malpighian body and uriniferous tubes.
   No. 28.  I repeated  this experiment on a large yellow  dog,
and in addition tied the ureters.   This animal  lived forty-eight
hours.   The Malpighian bodies were somewhat congested, and
of a yellowish red color.   I was much disappointed at the result
of this  experiment, as I could  not detect  the presence of bile
in any part of the kidney,  or in the urine, although I used most 
On the Function of the
carefully and repeatedly all the known tests for bile.  I then
made comparative tests with the bile from the gall-bladder of
this dog, and what was exceedingly surprising, I could not suc-
ceed in producing the usual peculiar appearances, either with
nitric acid, sulphuric acid and sugar, or any of the usual tests
for bile, even after most careful and repeated  trials.  I know
not to what this should be attributed.
    I had  long been anxious to obtain the kidneys of persons
who had  been in the habit of passing minute calculi of lithic
acid, or whose urine  constantly or usually deposited crystals of
lithic acid or the lithate of ammonia.  It seemed not unreason-
able to suppose, that by repeated examinations of such kidneys
under  the microscope, this  acid,  or  perhaps  even its com-
binations, might there be detected.   If found in the tubes alone,
its presence could be explained by the theory of Mr. Bowman,
viz., that  it was separated by  the epithelial cells of the  tubes
from  the  blood of the venous plexus  which surrounds them.
On the other hand, if found in the Malpighian tuft and capsule,
then we must believe that it was separated by that body.  My
friend, Dr. F.  U. Johnston, jun.,  has  kindly  presented me,
within a few days past, the kidneys taken from a child  three
months old.  These  contained  several very small  calculi of >
lithic acid, which were  situated in  the calyces  of the  kidney.
On making thin sections of the organ, the Malpighian bodies
were of a yellow color.   Some portions of the tuft were of much
deeper color than others, and seemed to contain reddish yellow
masses.  I endeavored, by using different  powers, to ascertain
whether these deeper-colored parts were crystalline, or had any
determinate form, but could  not succeed, after repeated at-
tempts, in resolving this question.  The tubes were not remark-
able.  I added a minute  portion of dilute nitric acid  to thin
sections, under the microscope,  and gently  heated the speci-
men over a spirit-lamp, and then exposed  it to the vapor of
ammonia; then  gently heating it again, placed  it under the
microscope.   The Malpighian bodies had become of a deep
red, and some of them of a beautiful  purple color.  I tried these
tests repeatedly with the same result.  Generally, the tubes
were not at first affected; but  on further application, many of 
Malpighian Bodies of the Kidney.
449
them assumed a red or  purplish red color.  I made compara-
tive tests with sections taken from the kidney of a cat, and also
from that of a sheep, testing them in the same manner.  In
these trials, however, the Malpighian bodies were  either ren-
dered of a dirty brown  color, or lost their color, being entirely
blanched.  I made somewhat thinner sections  of  the  child's
kidney, and on  gently heating them  with water and a little
nitric acid, effervescence took place, exactly as when lithic acid
is heated gently with nitric  acid.  On then exposing the speci-
men to the vapor of ammonia, or on adding a few drops of it,
and applying heat, a purple or reddish purple was produced.
Shall we infer that this was purpurate of ammonia, and if so,
that  as the  lithic acid was thus  found in the  Malpighian
body, it has the power, and does really separate it from the
blood ?  I shall content myself at present by simply stating the
facts, and  also my conviction that further researches in this
direction will probably settle the question.
    I  removed the kidneys  from a subject  who had died of
aneurism  of the aorta,  and whose  urine had  deposited  the
lithate of ammonia to  a very great  amount for a few days
previous to his  death.  In examining one of these kidneys, I
found the Malpighian bodies greatly  congested, and of  a dark
red color.  I then injected the renal artery of the other kidney
with  two ounces of water to half a drachm of nitric acid.   This
kidney was then laid aside for twenty-four hours.  I examined
thin sections of it under the microscope, but could not discover
any deposit in the tubes or in the Malpighian bodies.  I  placed
a drop of diluted nitric acid upon a thin section, heated it very
gently over a spirit-'lamp, and then exposed it to the vapor of
ammonia.  On placing it under  the microscope, the tubes and
Malpighian bodies were both of a reddish and  reddish  purple
color. I made comparative tests with thin sections from  the
fresh kidney of a cat, but in this case  the  color was entirely
destroyed by the application of the above reagents.
    I made some experiments to ascertain the effect of highly
stimulating diuretics upon the secreting  structures of  the
kidney.
   No. 29.  On the 24th of January I injected half an  ounce 
450               On the Function of the

of nitrate of potassa, dissolved in three ounces of water, into
the small intestines of a cat.  Ligatures were applied as in the
preceding  experiments.  This animal lived thirty-six hours.
The mucous  membrane of the intestines was very much in-
flamed.  The Malpighian  bodies were very  red and much
congested; many  of them were ruptured.  The  intertnbular
plexus was greatly congested.  The  mucous membrane of the
bladder was pale.
    No. 30. On the 21st of January.I injected into the oesopha-
gus of a cat half  an  ounce of tincture of cantharides, mixed
with three ounces of water.  This animal lived eighteen hours.
There  had been no symptoms of excitement of  the  genito-
urinary organs. The Malpighian bodies  were intensely red-
dened, and some of them were ruptured.   The venous plexus
was very much congested.  There was no inflammation of the
stomach or intestines ; on the contrary, their mucous coat was
pale, but that of the bladder was inflamed.
    No. 31.  January 2nd I injected six grains of phosphorus
in three ounces of  olive  oil, into the duodenum of a cat, a liga-
ture having been  placed above the opening into the intestine,
and another on the ileum, just above the ileo-ccecal valve.
After  an  hour, there  occurred great frequency of respiration
and circulation, paroxysmal efforts to bite at objects, and catch-
ing and  sparring  (as it were) with  the  paws, in the  most
ferocious  manner.   Gradually, great  prostration  and insensi-
bility  came on, with dilatation of the pupils.  She died three
hours  and a half after the operation.  The mucous membrane
 of the stomach and intestines was very pale.  The  Malpighian
 bodies were greatly congested, and some of them were ruptured.
 The intertubular plexus was much congested.  All these  parts
 were of a most brilliant red color, so that one of my friends
 remarked that " the specimen of the  kidney, under the micro-
 scope, seemed to  be  in a blaze of fire."  The kidney had a
 strong odor of phosphorus.
    No. 32. On the 30th of January I injected a grain and a
 half of phosphorus, dissolved in an ounce and a half of olive
 oil, into the small intestines of a cat.  This animal lived fifteen
 hours. The Malpighian bodies and venous plexus were very 
Malpighian Bodies of the Kidney.         451
red and much congested, but not so much as in the subject of
the preceding  experiment.   The  bladder was  slightly  con-
gested.  In neither of these animals in which phosphorus was
injected was  there any symptom of excitement  of  the genital
organs.
   No. 33. On the 2d  of February, at 6£ p.m., I injected an
emulsion of one ounce of spirits of turpentine, beaten up with
an egg, and three ounces of warm water, into the oesophagus
of a cat.   Four  hours  after, she seemed to be greatly pros-
trated, and was found dead  the next morning.   There was no
inflammation of  the stomach  or  intestines; the  bladder was
pale, and  contained urine,  which had the odor of turpentine.
The kidneys were greatly congested ; the  Malpighian bodies
filled with blood, and of a violet red, or rather a purple color.
Many of them, as well as the small arterial twigs upon which
they are placed, were ruptured.  There was also much conges-
tion of the venous plexus.
    The foregoing experiments then demonstrate the influence
of powerfully stimulating diuretics on the Malpighian bodies
and the venous plexus.

    Let us now  review the facts and arguments which thus far
throw light upon the function of the Malpighian tuft:

    1. That it is not for the  purpose of merely separating water
from  the  blood  is  proved  by its  distribution throughout the
substance of  the  kidney in  some animals whose urine is semi-
solid.
    2. The proximate elements of the urine exist ready formed
in the blood.
    3. These  elements can  only reach the kidney through the
renal artery,  upon whose minute terminal branches are placed
the Malpighian bodies.
    4. It has been shown that the Malpighian tuft is covered by
peculiar oval nucleated cells.  This glandular structure seems
to be, in every respect, well fitted for the separation of these
substances.
    5. The action of diuretics upon the Malpighian tuft. 
452
On the Function of the
   6. The actual separation by it of coloring substances, as
demonstrated by these experiments.
   7. The existence  of the coloring  matter of the bile in the
Malpighian tuft and capsule.
   8. The facts here  adduced relative to the presence of lithic
acid in the  Malpighian  tuft,  and its  detection  by chemical
tests.
   9. From all these considerations, it seems that we are justi-
fied in concluding that the Malpighian  tuft separates from the
blood most of the proximate elements of the urine.
   10. Any element  of the urine which is not secreted by the
Malpighian tuft is then probably separated by the epithelial
lining of the  tubes,  as is generally  believed.   This may  also
occur with certain foreign substances, which  have  been intro-
duced  into  the  circulation, and which the Malpighian  tuft
refuses to separate.   It is possible also that certain constituents
of the urine may be separated from the blood both by the tubes
and the Malpighian bodies.  All the facts, however, adduced
in this paper, lead to the conclusion that  it is to the Malpighian
body that we are to attribute the principal agency in the secre-
tion of the urine.
    I may here mention some  interesting facts which were
observed while making these  experiments.  The ferrocyanide
of iron or Prussian  blue, and indigo, are  both insoluble  sub-
stances, and are only held in suspension when mixed with water.
Inasmuch, however,  as they were absorbed and taken into the
circulation, we must either suppose  that  they were rendered
soluble by some substance met with in the intestinal canal; or
else, contrary to the  general opinion, that it is  not necessary for
a substance  to be soluble in order to be  absorbe'd, pass  into the
circulation, and then be separated  by the kidney.  As I had
ascertained that animal charcoal, an exceedingly insoluble  sub-
stance, could be found not only in the  kidney, but also in the
hepatic cells, and in  the  minute vessels  of the spleen,  I deter-
mined to try some  experiments with  other substances  well
known to be insoluble.
    No 34. On the 26th  December I removed the left kidney
of a cat, and placed a  ligature on  the right ureter.   I then 
Malpighian Bodies of the Kidney.
453
injected a mixture of very finely pulverized metallic bismuth
into the stomach and intestines, using  ligatures as usual.  The
cat died sixteen hours after  the operation.  The Malpighian
bodies and tubes were of a  light grey and of  a steel grey
color, resembling the impalpable powder of metallic bismuth.
No chemical tests were employed to ascertain its presence in
the kidney.
   No. 35. I caused a  book  of gold-leaf  to be very finely
ground with sulphate of  potassa.   This salt was then washed
away by water; the finely-powdered gold was then diffused
through water by agitation in a vial, and then poured into the
small intestine by means of a funnel, passed through the small
opening in the duodenum.  At the same time the left kidney
was  removed, and a ligature placed on the  right ureter.  The
dog lived twenty-four hours.   There was considerable  perito-
nitis, with effusion of pus and coagulable lymph.  There was also
some inflammation of the mucous membrane of small intestine,
and hemorrhage into the ileum.  The  Malpighian bodies were
of a yellow color, the tube somewhat darkened.  I could not
satisfy myself that gold existed in the kidney by examination
with the microscope.  1 also tried the  method by incineration,
both with the kidney and the liver, but could not detect  gold
in either organ.
   No. 36. I ground up  a book of gold-leaf with powdered
glass  into an impalpable  powder.   This  powder  was  washed
repeatedly with water to separate the siliceous portion,  and the
gold was mixed  up with a solution of  gum-arabic and injected
into the oesophagus of a dog.   The animal was killed about six
hours after injection, but I could not detect gold in the kidney.
   No. 37. On the 5th of January I removed the left kidney
of a cat and  ligated  the  right ureter. I then injected finely
precipitated copper, in an impalpable powder, into the stomach
and intestines, using ligatures in the usual  manner.  This cat
died in three hours.  The intestines were slightly, the stomach
intensely inflamed.   I could not detect the copper in the kid-
ney, either by the microscope, or by the method of incineration
in a porcelain crucible.
   No. 38. On the 30th of January I injected three drachms 
454
On the Function of the
 of finely precipitated copper into the oesophagus of a dog, and
 secured a brass pipe in it with a stopcock.   Twenty hours after
 I injected  the same quantity, suspended  as before  in water.
 He was killed two hours afterwards.   I incinerated one of the
 kidneys, in a porcelain  capsule,  with nitric acid; but, testing,
 could not detect  a trace  of copper.   Neither was I satisfied
 from the appearances under the microscope that this metal was
 present in the kidney.
    No. 39. On the 2d February, I injected into the oesopha-
 gus of a cat three  drachms of metallic  antimony, ground down
 to an impalpable  powder and well agitated with water at the
 moment previously to throwing in the injection.  The animal
 was killed five hours afterwards.  Many of the tubes were of a
 steel-grey color.   My young friend, Mr. Henry Draper, kindly
 tested one of the kidneys for me in the laboratory of the Uni-
 versity, but could  not detect a trace of  antimony in the kidney.
 I therefore consider this experiment as a failure, and also that
 all the other experiments with metallic substances were unsatis-
 factory,  and that the fact of their absorption and entrance into
 the  kidney has  thus far  not been  demonstrated  in  these
 instances.
    I may here  mention that the  introduction of coloring mat-
 ters into the kidney of animals by means of  absorption from the
 intestines and entrance into the circulation,  is a valuable means
 of facilitating the investigation of the structure of these organs
 The effect of stimulating diuretics  is also  of great  assistance
 in  this  respect.   It seemed to  me also  that  by ligaturing
 the abdominal  aorta a short distance  above its bifurcation a
 larger amount of blood would thus be thrown upon the kidney
 with the effect of congesting the Malpighian bodies and venous
 plexus.  Being unable, from sickness and other causes to carry
 out my design, I requested  my friend Dr. J. S. Goule'y, whose
 anatomical zeal and acquirements are deserving of the highest
praise, to perforin this operation, the results  of which we exam
ined together.   I beg leave here to express my sincere thanks
to him for his skillful and valuable assistance in nearly all of
my experiments.
   Nos.  40,41,43. I condense  from  Dr.  Gouley's  notes  of 
Malpighian Bodies of the Kidney.          455
three operations upon cats and dogs, in which he ligated  the
aorta, twice reaching the artery by an incision through  the
abdomen and once through the lumbar region, without wound-
ing the peritonaeum.  The symptoms, after tying the aorta, in
these three cases, were great acceleration of the heart's action
—pulsations so frequent that they could not be counted, no
pulsation in the femoral arteries, paralysis and coldness of the
inferior extremities, gradually increasing coma and diminished
frequency  of  respiration.   On dissection, the heart was  dis-
tended with coagulated blood;  lungs, slightly congested; liver,
nearly normal; kidneys, very highly congested.  Thin slices of
both  organs showed, under the microscope, the Malpighian
bodies enormously distended with blood; so much so', that on
looking at a very thin section with the naked eye, they could be
plainly distinguished.  Under the microscope, the tortuous ves-
sels of which the tufts are composed could be perceived more
beautifully than in an artificial injection.  Small vessels could
be seen sending branches on each side, terminating in the well
known round ball, all filled to their utmost.  The venous plexus
was also very highly congested. The intertubular vessels were
very  distinct, being  intensely congested.   Three or  four of
these specimens have been preserved.
    I  may here remark, that the injected state of the vessels
resulting from this operation greatly facilitates the  investiga-
tion of the structure of the kidney.  In connection with this
congested state  of the  Malpighian tufts and venous plexus, it
may not be uninteresting to refer to the operation of Sir Astley
Cooper for ligature of the abdominal aorta, in which case there
was suppression of urine for more than twenty-four hours.
    In conclusion, it may be well to consider what new facts or
deductions have been stated in this paper:
    1. It has, I think, been conclusively established, by numer-
ous experiments on animals, by repeated and  careful observa-
tions under the microscope, and by chemical tests, that colored
substances  are separated from the blood by the Malpighian
body.
   2. That the coloring matter of the bile is also separated by
it from the blood.
                            30 
456 Function of the Malpighian Bodies of the Kidney.

    3. From  the facts recorded in this  paper, it is very pro-
bable that it  may also separate lithic acid.
    4. That a new means of unravelling the  structure of the
kidney is afforded by such experiments.
    5. The peculiar action of excessively stimulating diuretics
has been demonstrated by their effect on the minute structures
of the kidney.
    6. The influence  of  ligature  of the  abdominal  aorta  in
throwing  an  increased afflux of blood upon the kidney, and
causing great congestion  of its minute vessels and capillaries.
    7. Incidentally,  some interesting  facts have  been stated
relative to the absorption of substances generally considered
to be insoluble. 
ADDENDA.
    My friend, Dr. Geo. T. Elliot, examined with me  this day,
 March 24th, 1857,  the  kidneys of a patient who had  been
 under treatment for paralysis  from lead for the last  seven
 months in Bellevue  Hospital, and who died of tetanus.  I made
 a  drawing of  the  epithelial cells,  both  of the straight and
 convoluted tubes, which, under the microscope, exhibited with
 the greatest clearness and distinctness the same ^appearances as
 seen in Plates 1 and 2 of this paper.
    I received from my friend, Dr. Geo. A. Peters, the kidneys
 of a child three months old, who  died with convulsions, the
 urine  having been  suppressed for  fifteen hours.   The  Mal-
 pighian bodies were very much congested, and of  a  dark red
 and purple colof.   The  intertubular plexus  was  also  much
 congested.  I  have also  noticed  that  the  kidneys  of other
 patients who had died from suppression of urine were  in  a
 similar condition.  This, taken in connection with the influence
 of  stimulating diuretics upon the  internal  structures  of the
 kidneys of the inferior animals, and the effect of  ligature  of
 the abdominal aorta in producing a similar result, would seem
 to show the importance of local depletion and counter-irritation
 in cases of suppression of urine and retention of urea in the
 blood, and the necessity of  avoiding diuretics, or  at least  of
 using them with great caution.
   The successful result of this mode  of treatment in  such
 cases is in  accordance with the views expressed in this paper
relative to the physiology and  pathology of the Malpighian
bodies and venous plexus.
END OF THE FIRST YOLCMI. 
 
INDEX.
Alga  Chocolate  and Biscuits, Report  on, by  the  Section on  Public Health
  and Legal Medicine,  .
Amputation of Thigh, and subsequent amputation of hip-joint, followed by
  perfect recovery, by W. H. Van Buren,    .....
Anaesthesia from Chloroform in Surgical Operations, on the importance of,
  by Valentine Mott,        .....
Aneurism  and Ligature of left Sub-Clavian Artery, case of, attended with
  peculiar circumstances, by V. Mott, .
Appendix, containing Minutes of Committee appointed to examine into em-
  ployment of injection into  bronchial  tubes, etc.,    ....
Atelectasis of the Lungs, by  S.  Conant Foster.
369
123
85
159
251
349
 Badly-united Fractures of  the  Thigh, cases  illustrating  treatment  of, by
   G. Buck,     ••••.....  191
 Barker, B. F., on Treatment of Puerperal Convulsions,      .       .      .273
 Bronchial  Tubes  and Tubular  Cavities  of the Lungs, on  injection  of, by
   Horace Green,      .......         203
 Buck, G., Casaof Croup in which Tracheotomy was successfully performed,   117
          On Treatment of Badly-united Fractures of the Thigh,    .      .191

 Chloroform, on the purity and use of, by J. T. Metcalfe,    .       .      .   139
             Precautions necessary m Administration of,    .             .   148
             Mode of Administration of,    .      .       .       .      .   151
             Means to be used when Anaethesia is carried too far in use of,.   152
 Cholera Infantum, Prize Essay on, by James  Stewart,      .       .      .   285
            On Etiology of,   .      .      .       .              .      .287
            General Phenomena of, .      .       .       .       .      .   297
            Morbid Anatomy of,    .....         299
            Pathology of,    .      .            ■ .       .       .      .   301
            Semeiology of,    .      .              .       .       .      _   315
            Treatment of,    ......         320
Convoluted Uriniferous Tubes, on termination of,     .       .             .   403 
460
Index.
Croup, Case of, in which Tracheotomy was successfully employed, by G. Buck,   117

Earle, Pliny, Historical Sketch of Institutions for the Insane in the United
  States,       .      •      •      •       •       •             •      .9

Foster, S. Conant, on Atelectasis of  the Lungs,       .       .       .      .349
Fractures of Thigh, Treatment  of  Badly-united  Fractures of, by Guedon
  Buck,..........191
Gardner, A. K., Report of Committee  on Comparative value  of Milk from
    Slop of Distilleries and other Food,      .       .       .       .  .    .   31
Green, Horace, on  Injections of Bronchial Tubes and Tubular Cavities of
  the Lungs,   .........   203
Griscom, John H., on Hospital Hygiene,     .       .   .    .       .      .167

Hospital Hygiene, illustrated, by J. H. Griscom,      .       .       .      .167

Injection  of the Bronchial Tubes  and  Tubular Cavities of the Lungs, by
  Horace Green,       .       .      .       .        .   ,   .       .      .   203
Institutions  for the Insane  in the  United  States, Historical Sketch of, by
  P. Earle,.........9
Isaacs, C. E., Researches into Structure and Physiology of Kidney,  .      .   377
             On Function of Malphigian Bodies of Kidney,  .       .      .   437

Kidney, Researches into the Structure and Physiology of, by C. E. Isaacs,  .   377
             On Function of the Malpighian Bodies of, by C. E. Isaacs,   .   437
             On Fibrous Matrix of, by C. E. Isaacs,   .       .       .      .418

Laceration of the Corpus Cavernosum Penis, commonly called  Fracture of
  the Penis, by Valentine Mott,    ...       .       .      .   99

Majority Report of Special Committee on Paper of Dr. H. Green on Injection
  into Bronchial Tubes and Tubular Cavities of the Lungs,   .       .      .   228
Malpighian Tuft of Kidney, Conclusion as to its connection with the Convoluted j
         Uriniferous Tube,    .......   401
             Body, Conclusions as to functions of,          .       .      .   407
             Bodies of the Kidney,  on the functions of,     .       .      .   437
Metcalfe, J. T., on the Purity and Use of Chloroform,        .             .139
Milk, Comparative Value of, from Slop of Distilleries and other Food, Report
  of  Committee upon, by A. K. Gardner,     .       ,       .       .      .31
             Solidified, Report on,           .       .       .       ,      .179
 Minority Report of  Special Committee on Paper of Dr. H. Green on Injection
  into Bronchial Tubes and Tubular Cavities of the Lungs,   .       .      .268
Mott, Valentine, on the Value of the Seton in Ununited Fractures,  .      .   71
             On the Importance of Anaesthesia from Chloroform in Surgical
               Operations,    .      .       .       .       #       ...   85
             On Laceration of the Corpus Cavernosum Penis,       . '     .99
             Case  of Aneurism and Ligature  of Left Subclavian Artery,
               attended with peculiar circumstances,       .       .      .159 
Index.
461
Puerperal Convulsions, on Treatment of, by B. F. Barker,  .      .       .273
             Diagnosis of from Epilepsy,     .      .      .      •       .275
             Causes of,        .......  275
             Treatment of,    .       .    '  .      .       .      .       .278
Report of Committee on Comparative Value of Milk formed from  the  Slop
      of Distilleries and other food,   .      .      .      .      .       .31
             On Solidified Milk,......179
             Majority, of Special Committee on Paper of Dr. H. Green on
               Injection into Bronchial  Tubes and Bronchial Cavities of
               Lungs,  ........  228
             Minority, of same Committee, on above Paper of Dr. H. Green,  268
             On Alga Chocolate and Biscuits,.....  367

Seton, on the Value of,  in Ununited Fractures, by V. Mott,  .      .      .71
Smith, Ashbel,  on the Diagnosis of Yellow and Bilious Fevers,     .      .51
Solidified Milk, Report on,     .      .       .      .      .      .      .179
Special Committee,  Majority Report, on Injection into  Bronchial Tubes and
   Tubular Cavities of Lungs,   .      .       .       ...      . .     .  228
             Minority Report on same subject,      ....  268
Stewart, James, Prize essay on Cholera Infantum,    .       .      .      .283
Structure and Physiology of the Kidney, Researches into, by C. E. Isaacs,  .  377

Thigh, Badly-united Fractures of, Cases illustrating treatment of, by G. Buck,  191
Tracheotomy, Cases of,  by W. H. Van Buren, .      .      .      .      .109

Van Buren, "W. H. Cases of  Tracheotomy,    .....   109
             Amputation of Thigh subsequent to Amputation at Hip-joint, .   123

Yellow and Bilious  Fevers, on the Diagnosis of, by Ashbel Smith,   .      .51 
I
I