48 AMPHIBIA. 



involuntary effort. For any other purposes the simple voluntary centres supplied by 

 the small brain suffice, as in fishes. With the lungs there is the first appearance of 

 a striated body and the choroid plexus. In both these classes the oblong medulla 

 bears a greater proportion to the size of the brain than in the higher, and seems to be 

 equally connected with the animal functions, and the lobes of the brain, as in them, 

 to be varied and superadded according to the required voluntary and other faculties. 

 The large size of the spinal cord, as compared with that of the brain, is also very 

 remarkable. When, therefore, the vast intricacy and number of the organs of the 

 body in both these classes are considered, and that they are nearly as great as in the 

 two higher classes, and when it is observed how small the size of the brain is in 

 proportion to the nerves, it must be concluded that both the oblong and spinal medulla 

 have peculiar and important functions ; as the nerves bear no proportion to the size 

 of the brain, but only to that of the oblong and spinal medulla, it must also be 

 concluded that their power is principally derived from these parts. 



