and Structure of the Proteus Anguinus . 103 
cent experiments of Dr Edwards ; but that the water so absorb- 
ed is conveyed into the aforesaid bladder is merely a conjecture ; 
and, as appears to the authors, wholly without foundation. But 
if we reject Townson’s conjecture, what must we think of the 
fluid with which the bladder, both in frogs and salamanders, 
is so frequently filled ? If it come not from the kidney, from 
what other gland or organ can it proceed ? Is it secreted by the 
bladder itself ? This supposition is not probable ; for the walls 
of the bladder are not sufficiently furnished with vessels to se- 
*/ 
crete so great a quantity of fluid. From some experiments not 
yet published, the authors are disposed to regard this organ as 
a true receptacle of urine. 
9. Of the Organs of Sense. 
The brain of the proteus very much resembles that of the sa- 
lamander, especially when in the larva state. The two hemis- 
pheres are nearly cylindrical ; the lateral ventricles are large, and 
in their posterior extremity lie the corpora striata. There is al- 
so a third ventricle, and two optic thalami, very small, and of an 
oblong form. The carotid artery, on entering the cranium, 
makes a twist around the aperture, and sends off the opthalmic 
artery, which is continued, between the cranium and hemisphere, 
to the eye : the principal trunk of this vessel then proceeds be- 
neath the brain, and, spreading into beautiful ramifications, is 
distributed to the two hemispheres, & c. See Fig. 4. Plate VI. 
The eyes of this animal are situated, and we might say buried, 
between the anterior extremity of the masseter muscles, which 
go to be inserted in the lower jaw, and the posterior extremity 
of the canal of the nostrils. They are inconceivably small, and 
are placed, not in an orbit formed by bone, but in a web or 
tissue, formed of venous and nervous ramifications. No muscle 
nor optic nerve has yet been discovered ; but on raising the he- 
mispheres very gently, a very subtile nerve, similar to the fine 
thread of a spider, seemed to go to the foramen, through 
which passed the ophthalmic artery, as seen in Fig. 4. The 
crystalline humour is large in proportion to the other parts, 
and has a spherical figure : the sclerotica is not white, but 
blackish ; of the other parts we dare not say more ; for, from 
their extreme minuteness, it is difficult to speak of them with 
precision. 
