THE VEGETATIVE PROCESSES OF THE BODY 649 



newborn puppies from which the motor region was extirpated suffered no sort 

 of motor disturbance, even immediately after the operation. This observation 

 teaches us that at a time when the pyramidal paths are not complete anatomically, 

 the motor region is incapable of any apparent physiological function, which is 

 borne out also by the fact that puppies begin to support themselves on their feet 

 only after the pyramidal paths have received their medullary substance. 



2. INFLUENCE OF THE CEREBRAL CORTEX ON THE 

 VEGETATIVE PROCESSES OF THE BODY 



In discussing the innervation of the different vegetative organs we have 

 from time to time called attention to the influence of the cerebral cortex 

 on their functions. In order to obtain a satisfactory conception of the cortical 

 functions, it will be necessary to summarize briefly these and other similar 

 phenomena in this connection. 



Artificial stimulation of the cerebrum, as we have seen, produces an epileptic 

 attack all too easily; and the excitation in such an attack is spread through the 

 subcortical centers to all the cross-striated muscles. At the same time the res- 

 piratory, cardiac and vasomotor centers, the centers controlling the digestive 

 apparatus and those of the iris, are also excited. But while this is of great 

 interest, it gives us no definite information with regard to the probable normal 

 influence of the cerebral cortex itself on these organs and their functions. 



In similar experiments on curarized animals, the epileptic attack is masked 

 because of the paralysis of the skeletal muscles, nevertheless the accompanying 

 phenomena in the vegetative organs make their appearance as usual. But these 

 experiments on curarized animals must not be trusted too far (Franck). It 

 appears that the influence which is exercised by the cerebral cortex on the vege- 

 tative processes proceeds in general from the motor region and its immediate 

 neighborhood. Indeed, Franck asserts that the effects which he has observed on 

 respiration, the heart, blood vessels and salivary secretion in the dog after stimu- 

 lation of the cerebral cortex can be obtained from almost the entire motor region, 

 but from no other points on the cortex. Respiration is accelerated or slowed 

 according to the strength of the excitation, just as in stimulation of the periph- 

 eral sensory nerves, and the depth of respiration is likewise affected. The glottis 

 becomes narrow with the tendency to expiration and becomes wider with the 

 tendency to inspiration, etc. With weak stimulation the pulse rate as a rule is 

 accelerated, with strong stimulation it is retarded. The blood vessels constrict. 

 We know also that salivary secretion and contractions of the urinary bladder are 

 influenced from the motor region (see page 239). 



Other authors, however, have reached different conclusions. According to 

 Horsley and Semon, the muscles of the vocal cords and of the larynx in the 

 monkey have their cortical area in the lowermost part of the central convolu- 

 tions and within this region the following definite movements can be localized: 

 (1) bilateral adduction of the vocal cords; (2) the same movement, plus move- 

 ments of the pharynx; (3) elevation of the larynx, accompanied by movements 

 of the face, the jaws and the tongue; (4) depression of the larynx. 



Spencer has obtained the following effects on the respiratory movements by 

 stimulation of the cerebral cortex in several different species of animals (mon- 

 key, dog, cat, rabbit) : slowing and stoppage of respiration by stimulation of 

 the border of the temporal-sphenoidal lobe lateral to the base of the olfactory 

 tract; acceleration of respiration by stimulation of the convex upper surface in 



