390 BIOGRAPHICAL SKETCHES. 



decisively by similar appeal, an extract from which I beg 

 leave to append in a note. 1 



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 distiuct. 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 vertebrae which compose the 



1 " If 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." 



