The Nervous System. 



181 



the ascending frontal convolution, a locality corresponding to the 

 seventh center of Ferrier, when injured, causes twitching of the zygo- 

 matic muscles on the opposite side. A point injured on the right 

 ascending parietal convolution, produces twitching and paralysis of 

 the muscles of a part of the left leg. Charcot, Hitzig and Cruveilhier 

 have given testimony which substantiates the observations of Ferrier. 

 Although this field of inquiry has not been cultivated but a few years, 

 enough has already been discovered to show that earlier views of the 

 functions of the encephalon were decidedly erroneous. 



It is now generall} 7 believed that conscious intelligence does not 

 have its seat in &ny particular part of the brain structure, but that it 

 needs at least one half the cerebrum — a hemisphere — for an abode. It 

 is known that one side of the cerebrum may be atrophied or destroyed, 

 and intellection will be kept up by the sound half. 



Y\y comparing the general arrangement of the convolutions in differ- 

 ent animals, it is found that the brain of the cat, for instance, presents 

 few sinuosities or foldings, and these run in parallel ridges, the course 

 being antero-posteriorly. The brains of the fox and the wolf show a 

 similar arrangement of gyri, except the}^ are a little more flexuous. The 

 brain of a sheep has more cerebral gyrations than that of the beaver, 

 yet the latter animal is far more circumspect in its general habits of 

 living. The sheep is proverbiallv aimless and stupid. The complex- 

 ities in the arrangement of the brain of the dolphin equal the disposal 

 of the convolutions in man, } r et the former can not be esteemed as 

 especially intellectual. It is certain, however, that the convolutions of 

 the cerebral hemispheres of idiots are disposed in horizontal or perpen- 

 dicular tiers, and are not so ''oblique" in direction, and flexuous as 

 they are in the strong minded of our race. 



The development of the cerebrum backward is a notable feature of 

 the human encephalon. In man the cerebellum is complete^ overshot, 

 while in the higher apes the posterior lobes of the cerebrum barely 

 cover the ''lesser brain." In the encephalon of the horse, the cere- 

 bellum is almost uncovered ; and in felines the cerebrum, resting upon 

 an osseous tentorium, does not extend as far backward as the cere- 

 bellum. And, as the scale of being is followed downward, the dispro- 

 portion between the "little" and the "great" brain lessens, till, at 

 length, they are nearly the same size, and are arranged on about the 

 same level. 



From the lowest to the highest of vertebrates there exists a serial 

 gradation in the scale of intelligence. There is a vast difference be- 

 tween the mental qualities of man and those of a trogloctyte; and so 



