NERVOUS SYSTEM 159 



struction of the cerebrum of the various animals and must 

 always be taken into consideration in homologising the fissures. 



A comparison of the weight of separate portions of the 

 brain with that of the large hemispheres, or of the entire 

 brain, yields very instructive figures. Thus Meynert (following 

 Joh. Muller) takes the proportion borne by the cerebral hemi- 

 spheres to the corpora quadrigemina as the unit of measurement, 

 and finds that in proportion as the hemispheres develop, the 

 peduncle of the crus cerebri (containing the voluntary motor 

 nerves) surpasses in bulk the tegmentum of the crus cerebri. 



On the authority of Huschke, 1 the weight of the optic 

 thalamus and corpus striatum is as follows : 



/ of the weight of the cerebral hemispheres. 



13 

 calf 

 sheep 14- 1 5 ,. 



Huschke 2 has further tabulated the proportion of the cere- 

 bellum (Vermis, lobes, Pons Varoli and Medulla oblongata) to 



the entire brain. His results are the following : 



In man . . . 12-13 / cerebellum. 



the gibbon . . 13-91 



cow 12 



dog . 11-17 ,. 



horse . . 15-17 



fox . . 15-18 



goat . 17-18 



Pig- i ,. 



sheep . . 17-21 



ii bear 19 



cat . . . 20-23 



rabbit . 24 ,, 



rat . . . 25-27 



,, duck-bill . . 25 



raven . . 10-13 



wood-pecker . 14 



Huschke, loc. cit., p. 104. *lbid., p. 73. 



