SPINAL MARROW. 151 



which gives origin to the 'two longitudinal crura of 

 the medulla oblongata. 



" 9. It also appears, that there exist certain relations be- 

 tween the faculties of animals, and the proportions of their 

 common parts. 



" Thus the intelligence they possess, appears more per- 

 fect in proportion to the volume of the appendix of the cor- 

 pus striatum, which forms the vault *>f the hemispheres. 



" Man has that part greater, more extended, and more 

 reflected than the other animals. 



" In proportion as we descend from man, we observe that 

 it becomes smaller and smoother on the surface, and that 

 the parts of the brain are less complicated with each other, 

 but seem to be unfolded and spread out longitudinally. 



"It even appears that certain parts assume, in all classes, 

 forms which have a relation to particular qualities of ani- 

 mals : for example, the anterior tubercula quadrigemina of 

 carps, which are the most feeble and least carnivorous of 

 fishes, are proportionally larger than in the other genera, 

 in the same manner as they are in the herbivorous quadru- 

 peds. By following these inquiries, we may hope to obtain 

 some knowledge of the particular uses of each of the parts 

 of the brain *." 



In the animals without vertebrae., the brain is -destitute 

 of the protecting bony covering, which forms the head and 

 backbone in the vertebral animals. The brain itself is 

 much more simple in its structure. The cineritious and 

 medullary parts, can scarcely be perceived as distinct ; and 

 all that appears to be present is a cerebellum, with one or 

 more tubercles, resembling a cerebrum, and nerves fur- 

 nished with ganglia. 



Independent of very remarkable differences in the struc- 



* Comparative Anatomy, vol. ix. p. 8. 



