72 THE POPULAR SCIENCE MONTHLY. 



for organic functions of a lower kind. This is not the place to describe 

 the special functions of these different sorts of nervous centres which 

 are superposed and in a manner ranged along quite into the spinal 

 marrow; it is enough to say that we owe the knowledge of them to 

 that method of vivisection by organic removal which is adopted in a 

 general way in all physiological inquiries. Here the brain behaves in 

 exactly the same way as all the other bodily organs, in this sense, 

 that every lesion of its substance produces characteristic disturbances 

 in its functions, which always correspond with the mutilation effected. 



By means of the cerebral lesions he produces, the physiologist does 

 not stop at the creation of local paralysis, which suspends the action 

 of the will on certain organic instruments ; he is able also, by merely 

 disturbing the equilibrium of cerebral action, to produce a suspension 

 of freedom in voluntary motion. Thus, by injuring the peduncles of 

 the cerebellum, and different points of the brak, the experimenter can 

 make an animal move as he chooses, to right or left, forward or back- 

 ward, or can make it turn, sometimes by leaps, sometimes by rotary 

 movement on the axis of its body. The will of the animal persists, 

 but power to guide its motions is gone. In spite of its efforts of 

 will, it moves necessarily in the direction determined by the organic 

 lesion. Pathologists have remarked numerous similar instances in 

 man. Lesions of the peduncles of the cerebellum create rotary move- 

 ments in men as in animals. Some patients could walk only straight 

 onward. In one case, cruel in its irony, a brave veteran general could 

 only move backward. Therefore the will, which proceeds from the 

 brain, does not take effect on our organs of locomotion themselves ; it 

 impresses itself on secondary nervous centres, which need to be kept 

 harmoniously balanced by a perfect physiological equilibrium. 



There is another and more delicate experimental method, which 

 consists in introducing into the blood various poisonous substances 

 intended to exert their action upon the anatomical elements of the 

 organs, while these are left undisturbed and kept uninjured. Aided 

 by this method, we can extinguish separately the properties of certain 

 nervous and cerebral elements, in the same way that we can also sever 

 the other organic elements, whether muscular or sanguine. Anaes- 

 thetics, for instance, destroy consciousness and depress sensibility, 

 while they leave the power of movement untouched. Curare, on the 

 other hand, destroys the power of movement, and leaves sensibility 

 and will unimpaired; poisons affecting the heart, suspend muscular 

 contractility, and the oxide of carbon destroys the oxidizing properties 

 of the blood- globules, without at all affecting the properties of the 

 nerve-elements. As we see, by this method of investigation or ele- 

 mentary analysis of organic properties, the brain and those phenomena 

 that have their seat in it may also be affected in the same manner as 

 all the other functional instruments of the body. 



There is yet a third method of experimenting, which may be called 



