390 BIOGRAPHICAL SKETCHES. 
decisively by similar appeal, an extract from which I beg 
leave to append in a note.! 
So, in describing the structure of the optic nerves in the 
frog, and the development of the eye and optic lobes, he pro- 
ceeds to remark : — 
“The instances of Proteus and Amblyopsis naturally sug- 
gest the questions, whether one and the same part may not 
combine functions wholly different in different animals, and 
whether the same may not hold true with regard to the cere- 
bral organs which is known to obtain with regard to the 
skeleton, the teeth, the tongue, and the nose, that identical or 
homologous parts in different animals may perform functions 
wholly distinct. If the doctrine here suggested can be admitted 
(and if this were the place, facts could be cited in support of 
it), may we not find in it an explanation of many inconsis- 
tencies which now exist between the results of comparative 
anatomy and of physiology ?” 
Then, in his chapter on the philosophical anatomy of the 
cranial nerves and skull, after showing that there are but three 
pairs of cranio-spinal nerves, he takes up the controverted 
question as to the number of vertebre which compose the 
1 «Tf by force is meant the muscular energy and development of the 
limbs, this statement does not appear to be sustained in the present in- 
stance, nor in many other instances brought to notice by comparative 
anatomy. In man the brachial enlargement is always larger than the 
crural, though the legs are so much more powerfully developed than the 
arms, and the same is true of the greater number of mammals. In frogs 
there is a still greater disproportion between legs and arms, yet there is 
not a corresponding difference in the size of the bulgings. They cannot, 
therefore, be said to be in proportion to the muscular force only of the 
limbs, but correspond far more nearly to the acuteness of the sense of 
touch, which in man and mammals is more delicate in the hands and arms 
than in the legs and feet. In bats, it is true that the muscular force of 
the arms is greater than that of the legs, and that the brachial far sur- 
passes the crural enlargement ; but, at the same time, the sense of touch 
in the membranes of the wings is exalted to a most extraordinary degree. 
In birds the posterior bulging is almost universally the largest, though 
this condition is in part dependent upon the presence of the rhomboidal 
sinus. In these animals, while the muscular energy of the wings is the 
most developed, the sensibility of the feet is the more acute.” 
