7 o THE POPULAR SCIENCE MONTHLY. 



that end in closing the fist ; in connection with these centers we may 

 note Nos. 4 and 5 ; they produce movements of the opposite arm and 

 hand. It is plain that 4 and 5, and a, b, c, d, are closely related to one 

 another. 



According to the theory of localization of functions, we should 

 expect the centers, a, b, c, d, to be extensive in the monkey's brain, 

 and to be wanting in the brains of lower animals. As matter of fact, 

 they are absent in cat, dog, and jackal, except that a is found in the 

 brain of the cat. This animal uses the front-paw for seizing and hold- 

 ing. Upon stimulating center No. 6, the fore-arm bends, and the hand 

 lifts to the mouth. This movement is constant with the monkey. 

 There is no corresponding center in the brain of the dog or cat. The 

 centers marked 7, 8, 9, 10, 11, are all concerned with movements of 

 the mouth such as elevating the angle of the mouth, depressing 

 the lower lip, thrusting out and withdrawing the tongue. No. 12 

 lies quite to the front of the brain ; when it is stimulated, the eyes 

 open widely, the pupils dilate, head and eyes turn toward the oppo- 

 site side. 



These are the centers in the brain which, by some authorities, are 

 thought to have a purely motor significance. The centers marked 13, 

 13', 14, and 15, give movements the former of the eyes, the latter 

 of the nostrils but they are believed to be primarily connected with 

 sensations. 



Aside from the centers enumerated, no other parts of the brain 

 respond to stimulation. 



I have purposely stated the results of Ferrier's earlier experiments 

 on the so-called motor zone. These experiments have been, in general, 

 confirmed by other investigators. That is to say, the movements 

 above described have been found by many to follow stimulation. It 

 is, however, a part of the present confusion and contradiction which 

 prevails respecting cerebral localization that the interpretation of these 

 movements is disputed. 



Munk appears (" Transactions of the Physiological Society of Ber- 

 lin," 1876-1878) with a series of experiments which, as he thinks, 

 prove that the motor zone is primarily a zone of feeling. He there- 

 fore divides this portion of the brain into spheres of feeling one for 

 the forward limbs, one for the head, one for the eyes, one for the ears, 

 etc. Munk believes that the animal's movements are affected by 

 destruction of these centers, because four distinct kinds of feeling are 

 destroyed. For example, loss of the center concerned with movements 

 of the fore-limb would, according to Munk, cause a loss 1. Of the 

 consciousness of pressure on the limb ; 2. Of the consciousness of the 

 position of the limb ; 3. Of the consciousness of the motions belong- 

 ing to the limb ; and, 4. Of the consciousness of touch in the limb. 

 Whereas Ferrier and others find sensibility, both general and special, 

 intact after destruction of these motor regions, Munk finds a loss of 



