PROTEUS ANGUINUS. 
Amcr..Tour.Sci. Vol. W Plate III. SOME ACCOUNT 
OF THE 
PROTEUS ANGUINUS. 
By JOHN C. DALTON,Je.,M.D. 
■WITH A PLATE. 
[Extracted from the American Jour, of Science and Arts, 2nd Series, Vol. XV, May, 1853.] ON THE PROTEUS ANGUINUS. 
In the Austrian province of Carniola there are a large number 
of grottoes, the two most remarkable of which are in the imme- 
diate vicinity of Adelsberg, a small post-town, about thirty-five 
miles inland from Trieste. The larger of these, which is the 
only one usually visited by travellers, and which is justly cele- 
brated for the extent of its passages, and for the elegance and va- 
riety of its stalactites, has its entrance on the side of a hill, about 
fifteen minutes’ walk from the village. It is called by the in- 
habitants the “Grotto of Adelsberg.” A small stream flows into 
its mouth, but disappears after a short distance through one of 
the numerous chasms which open into the principal passage. The 
grotto penetrates the hill in a nearly horizontal direction, and can 
easily be followed for a distance of one to two miles. It has 
also been explored for nearly twice that distance, but the passage 
is difficult and dangerous, and its termination has never yet been 
reached. In the waters of this cavern there are found occasion- 
ally a few crabs and fishes, of the same species as those met 
with outside, and which have been carried in by the stream 
that enters at its mouth. There is, however, another grotto, 
situated about a mile farther from the town, called the “Magda- 
lena Grotto,” the waters of which contain the curious species of 
reptile known as the “.Proteus anguinus.” This is the only 
place in the vicinity of Adelsberg where the animals are met 
with ; and though they exist also in other parts of Carniola, they 
are more abundant in the Magdelena Grotto than elsewhere. 
Unlike the “Adelsberg Grotto,” this cavern receives no stream 
at its mouth, and penetrates the hill in a steep downward direc- 
tion, instead of horizontally. After descending, for about fifteen 
minutes, by an exceedingly rough and irregular passage, partly 
rocky and partly covered with soft mud, the visitor comes to a 
pool of still water, varying from 12 to 18 feet in depth, according 
to the season, beyond which the cavern cannot be explored. It 
is in this pool that the Proteus is met with. The water appa- 
rently communicates with that of the Adelsberg Grotto; as it is 
always turbid when the latter is so, and vice versa. Both cav- 
erns are, of course, perfectly dark, and can be explored only with 
torches. The temperature, in the latter part of August, was 
about 40° to 50° F., and probably does not vary much through- 
out the year. It is certain, at least, that in winter it is much 
higher in the interior of the grotto than outside. The Proteus 
is taken in small hand-nets by the peasants, who watch for the 
animal as he lies almost motionless near the bottom of the pool, 
and capture him by a sudden motion of the net. They are not J. C. Dalton, Jr., on the Proteus anguinus. 
3 
very abundant, however, and as they can be taken only when 
the water is perfectly clear, it is seldom that more than 15 or 20 
are obtained during the course of a year. The animals should 
be kept afterward in obscurity, and at a temperature as nearly as 
possible resembling that of the grotto. It is necessary, also, to 
change the water in which they are kept regularly every day. 
With these precautions it is said they may be preserved alive for 
an indefinite length of time. I have myself kept one of them 
for several weeks without giving it any food, and at the end of 
that time it was as active, and nearly as well-conditioned as ever; 
only the branchiae had become somewhat smaller. I am told by 
Mr. Fitzinger, the Superintendent of the Department of Reptiles 
in the Vienna Zoological Museum, that they have been kept at 
the Museum for over six years, without any other food than the 
organic matters usually existing in fresh water. 
It is very commonly believed that the Proteus is found only in 
the Magdalena Grotto. This, however, is an error ; as it appears, 
by a report of Mr. Fitzinger’s to the Imperial Academy of Sci- 
ences, in Oct. 1850, that there are no less than thirty-one differ- 
ent localities in which the animal is said to have been found since 
it was first discovered in 1751. Mr. Fitzinger, himself, has seen 
specimens from eleven different localities. Of these the Magda- 
lena Grotto supplied much the greater number, viz.: 312 out of 
479. The reporter states that, in almost every instance, the ani- 
mals coming from different grottoes, present such striking pecu- 
liarities in size, color and shape, that they cannot be considered 
as belonging to the same species. Accordingly, he rejects the 
the old name of Proteus Anguinus and adopts instead the generic 
name “Hypochthon.” In this genus he comprises seven differ- 
ent species, as follows: 
Hypochthon Zoisii, 
“ Schreibersii, 
“ Freyeri, 
“ Haidingeri, 
Hypochthon Laurentii, 
“ xanthostictus, 
“ Carrarae. 
Six of these species are found in various grottoes of Carniola, 
and the seventh in Dalmatia. Two different species never exist 
together in the same locality, though sometimes the same species 
is found in more than one grotto. One of the principal marks of 
distinction is their size; the maximum length of the different 
species varying from 9J to Ilf inches. The tint of the skin is 
in some species more rosy, in others yellowish. The head is 
pear-shaped, triangular, or more globular in form. The eyes, 
also, are more distinctly visible in some species than in others, 
and vary somewhat as to their situation. 
The living specimen from which the drawing for the plate 
was made (fig. 1) came from the Magdalena Grotto. It be- 
longs to the smallest of the species described by Mr. Fitzinger, 4 
J. C. Dalton, Jr., on the Proteus anguinus. 
viz.: the H. Laurentii. Specimens of two other species, the 
H. Haidingeri and H. Freyeri were obtained afterwards at the 
Vienna Museum for purposes of dissection. 
The body of the animal is cylindrical, like that of an eel, with 
its posterior portion compressed laterally into a kind of vertical 
membranous fin. There are four extremities, the anterior three- 
toed, the posterior two-toed. The posterior are considerably 
smaller and more feeble than the anterior. The first circum- 
stance which strikes the notice of the observer is the almost en- 
tire absence of color, and the transparency of the tissues, which 
allow the cutaneous and subcutaneous vessels, and even the veins 
and arteries of the extremities to be perceived without difficulty. 
The heart can be distinctly seen through the skin, at the anterior 
part of the neck, beating 48 to 50 times per minute. The 
dark color of the liver, also, shows through the integument 
very plainly on the under surface of the abdomen. The whole 
aspect of the animal reminds one very strongly of the foetal con- 
dition of the higher vertebrata, particularly about the extremities, 
where the transparency of the integuments shows to best advan- 
tage. Notwithstanding, however, its delicacy and apparent fee- 
bleness, its motions are occasionally very rapid and energetic. 
They consist of swift undulating movements of the eel-like body 
and tail. The limbs are nearly useless during rapid progression, 
and remain almost motionless, applied to the sides of the body. 
It is only in the slow motions of crawling and turning, that the 
extremities are used, and then only in a feeble and imperfect 
manner. The gills, three in number on each side of the neck, 
are in the form of long tufts; each principal stem being divided 
into six or seven branches, and these again subdivided into fine 
twigs. When the Proteus is in rapid motion, they become dis- 
tended with blood, and of a bright scarlet color, contrasting finely 
with the light yellowish, indefinite hue of the rest of the body. 
In a state of rest, however, they are often perfectly pale, like 
any other part of the surface. The animal occasionally lifts its 
head above water and takes in air by the mouth or nostrils, 
which, after remaining sometime in the lungs, is expelled through 
the branchial fissures in the sides of the neck. Notwithstanding 
this frequent inspiration of air, however, and the large size of 
the lungs, the pulmonary respiration is a very imperfect one and 
altogether secondary to the branchial. It is said that in a moist 
and cool place, as, e. g., on the floor of the Magdalena Grotto, 
the Proteus can live many hours, carrying on its respiration by 
the lungs and through the skin only; but in a warm apartment 
it expires in a few minutes after being taken out of the water; 
particularly if the skin is wiped dry, as I have myself ascertained 
by trying the experiment. Over the whole surface of the skin, 
from the anterior part of the head nearly to the end of the tail, /. C. Dalton, Jr., on the Proteus anguinus. 
5 
there are minute punctiform openings, the orifices of cutaneous 
follicles, which exude an abundance of transparent colorless mu- 
cus. The peritoneal cavity is also filled with a similar exudation, 
There are but few peculiarities.about the skeleton. The bod- 
ies of the vertebrae are articulated to each other by concave sur- 
faces as in the fishes, instead of one of the articulating surfaces 
being concave and the other convex, as is the general rule among 
reptiles. The anterior extremities consist of a cartilaginous cla- 
vicle and scapula, fused into a single piece, a humerus, radius and 
ulna, three carpal pieces, and three digits, the two inner ones of 
which have three phalanges each, and the outer one, which is 
shorter, only two. The posterior extremities are supported by 
a simple pelvic ring, resting against the sides of the vertebral col- 
umn. They are composed of a femur, tibia and fibula, a tarsus 
composed of three pieces, precisely similar to those of the carpus, 
and two digits of three phalanges each. All these parts are en- 
tirely cartilaginous, or so slightly ossified that it is difficult to be 
sure whether there is any true bony formation or not. The snout 
is rather broad and thick. The nostrils open on the under sur- 
face of the upper lip, as in Lepidosiren Paradoxa. They are 
continued into a cylindrical, membranous canal, something less 
than a third of an inch long, situated in the thickness of the 
lip. There is a long row of fine, sharp, conical teeth in both 
upper and lower jaw; and in the upper, there is also a second 
much shorter row, in front of the first. The tongue is errone- 
ously stated by R. Wagner (Comp. Anat. Vertebrata) to be want- 
ing. It is, on the contrary, very easily seen; about one-eighth 
of an inch long, but consisting only of mucous membrane and 
adipose tissue. The animal has the vertical stomach and short 
intestinal canal of the allied genera. The anus is a longitudinal 
slit, just behind the junction of the posterior extremities with the 
body. The liver is a long, lobulated organ, wrapped round the 
stomach and upper part of the intestinal canal, and extending 
nearly two-thirds the whole length of the abdominal cavity. 
The heart, enclosed in a pericardium, is composed of a single 
auricle and ventricle. The arterial trunk arising from the ventri- 
cle is partially converted into a double canal by an imperfect lon- 
gitudinal partition. It sends off, on each side, three branchial 
arteries, and the returning branchial veins unite immediately be- 
low the situation of the heart, to form a single descending aorta. 
The lungs are simple, elongated, thin, membranous sacs, secured 
by a fold of peritoneum against the posterior abdominal wall, and 
somewhat unsymmetrically developed. The left runs down, 
from its opening into the oesophagus, nearly three-quarters the 
whole length of the abdominal cavity; the right but little over 
one-half the length. The blood globules of this animal have 
been long known to be remarkable on account of their large size. 6 
J. C. Dalton, Jr., on the Proteus anguinus. 
They can be easily found almost unaltered in the blood vessels, 
and particularly in those of the gills, even in specimens which 
have been kept for a long time in spirit. They are of a flattened 
oval shape, like those of the frog, with a central, white, granular, 
roundish nucleus, also somewhat flattened. The length of the 
globules varied, in the specimen examined, from *0016 to 0023 
inch. The breadth is usually -0013, and the thickness -0003. 
As this last measurement is exactly the diameter of the human 
blood globule, some estimate may be made of the difference be- 
tween them. In fig. 4 the blood globules of human blood, of 
the frog, and of the Proteus (a, b, and c) are magnified in the 
same proportion, in order to show their relative sizes. The mus- 
cular fibres of the body are also very large, and very distinctly 
striated. Their diameter varies from -0019 to 0036 inch. The 
nerve-fibres were not remarkably large, those from the facial 
measuring only *00027 inch in diameter. 
The two most interesting peculiarities of the animal, taken in 
connexion with its subterranean mode of life, are the colorless 
condition of its skin, and the imperfect development of its visual 
organs. At first, the eyes seem to be altogether wanting; but 
on close examination, they may be discovered, in the recent state, 
two minute blackish points, situated about the junction of the 
anterior and middle thirds of the head (fig. 1). When the ani- 
mal has been preserved in spirits, it is sometimes impossible to 
distinguish them until the integuments have been removed. 
They are then found lying immediately beneath the skin, imbed- 
ded in a small quantity of adipose tissue (fig. 2). In an individ- 
ual measuring S| inches in length, the eyeball was of an 
inch in diameter; and the optic nerve, just before joining the 
globe, g|¥nd of an inch. Notwithstanding its minute size, how- 
ever, the eye is sufficiently well developed as to its structure. 
The sclerotic is covered with brownish spots, mostly hexagonal 
in shape, and which are more thickly crowded and deeper in 
shade just at the margin of the cornea, where they form a black- 
ish ring (fig. 3). The crystalline lens is globular, and T of 
an inch in diameter. There were some appearances of a nearly 
colorless iris, lying behind the cornea, but the parts were so mi- 
nute that I did not succeed in ascertaining its existence by dis- 
section. The brain is pretty well developed, though less so than 
in other allied genera; and notwithstanding the imperfect condi- 
tion of the eyes, the lobes which, in the brain of reptiles, are 
usually considered as representing the Tubercula Q.uadrigemina, 
are of very considerable size. The brain of the Triton cristatus, 
another naked Amphibian, with large well developed eyes, differs 
from that of the Proteus simply in being rather larger in com- 
parison with the size of the animal, and in having a somewhat 
greater proportional development of the hemispherical lobes. The J. C. Dalton, Jr., on the Proteus anguinus. 
7 
following are the longitudinal measurements of the brain of a 
Triton cristatus, 61 inches long, and that of a Proteus anguinus, 
8} inches long: 
Triton. Proteus. 
Hemispherical lobes, 5 millimetres. 4| millimetres. 
Tubercula Q,uadrigemina, 2£ “ 2£ “ 
Cerebellum, . 1£ “ 1J “ 
The two brains could hardly be distinguished from each other, 
except for the fact that the olfactory nerve in the Proteus runs 
forward for some distance as a trunk along the inner side of the 
membranous olfactory canal, while in the Triton it breaks up 
into branches immediately on leaving the anterior extremity of 
the brain (fig. 5). 
It will be seen that the suppression of the visual organs ill 
these animals is not, by any means, complete. There are, how- 
ever, other creatures existing in the same localities with the Pro- 
teus, in which the eyes are altogether absent. Two species of 
Crustaceans are found in the caves of Carniola, viz: Palasmon 
anophthalmus and Titanethes albus, both of which are color- 
less, diminutive in size (not more than one inch long), and, so far 
as they have been examined, entirely destitute of eyes. They 
are supposed by some to be the natural food of the Proteus. I 
am informed by Mr. Kollar, of the Vienna Zoological Musuem, 
that a species of spider, entirely blind, has also been discovered 
in the same caverns. 
There is much resemblance, in regard to the condition of the 
eyes, between the Proteus and Lepidosiren Paradoxa. In the 
two specimens of Lepidosiren, dissected by Prof. BischofF, and 
described by him in a monograph on the subject, the eyes were 
“hardly a line in diameter,” though one of the animals measured 
over three feet in length. The opening of the eyelids is want- 
ing, also, in Lepidosiren as in Proteus, and the eyeball is com- 
pletely covered by the integument. So little is known, however, 
of the mode of life of Lepidosiren, that it is impossible to deter- 
mine whether the cause of the imperfection be the same in both 
animals. 
Very little is yet known with regard to the mode of reproduc- 
tion of the Proteus; and, particularly, it is altogether uncertain 
whether the animals are oviparous or viviparous. Dr. Joseph 
Hyrtl, Professor of Anatomy at the University of Vienna, states 
that he has found, at the extremity of the oviduct in the Proteus, 
a gland which exists elsewhere only in the oviparous species of 
the naked Amphibia; so that the Proteus is probably also ovipa- 
rous. But nothing more definite has been discovered. One Ger- 
man observer (von Schreibers) endeavored to ascertain this point 
by examining specimens of Proteus, taken from their caverns at 
every season of the year; but, according to Herr Fitzinger, he 8 
J. C. Dalton, Jr., on the Proteus anguinus. 
only succeeded in finding the ovaries unusually developed in a 
few instances. H. Fitzinger, himself, has met with the ovaries 
in a state of active development in only one instance; and up to 
the present time, according to him, neither ova nor embryos have 
ever yet been discovered in the oviducts. 
The female generative organs consist of two elongated, sacci- 
form ovaries, situated at the posterior part of the abdomen, direct- 
ly in front of the kidneys. In the specimen measuring 8} inches 
total length, in which the generative organs were in a state of 
quiescence, the right ovary was 0 98 of an inch long,—the left 
somewhat smaller. The cavity of the organs was lined by a 
mucous membrane, beneath which were to be seen the whitish, 
globular, nearly transparent ova, varying in diameter from 7'5th 
of an inch downward. The oviducts were a pair of slender and 
perfectly straight tubes, which, commencing by a wide aperture, 
at some distance anterior to the ovaries, and running down on the 
•outer and posterior aspect of these organs, opened into the clo- 
aca, just above the orifices of the ureters. 
In another specimen, however, obtained at the Vienna Muse- 
um, the organs were in a high state of development. The right 
ovary was I 75 inches, the left V64 inches long, and they con- 
tained, together, 66 roundish, opaque ova, of a deep yellow color, 
and evidently just ready to be discharged. Their average size 
was a little less than |th of an inch in diameter. The oviducts 
were much larger than in the other specimen, and exceedingly 
contorted, so that they must have attained two or three times their 
ordinary length. None of the ova, however, had yet left the 
ovaries, so that nothing new could be learned with regard to the 
question of viviparity.