258 HUMAN BIOLOGY 



The nervous organ (the bulb) which immediately directs 

 and executes swallowing is a lower non-mental center 

 Hke the cerebellum and the spinal cord. The mental organ, 

 however, is able to get into touch with the bulbar organ. 

 The swallow, moreover, is unlike the previous steps in the 

 train of behavior directed toward obtaining food, since it 

 cannot be initiated by the mental organ per se. We cannot 

 swallow unless we have something to swallow; the act is 

 essentially a reflex and requires a local stimulus. Further, 

 when once initiated it cannot be arrested by the mental 

 organ; it must take its course, hence the bitter powder once 

 placed at the back of the child's tongue is safe from refusal if 

 the swallow starts. And the final step of transit down the 

 gullet is so wholly reflex, and the nervous system which it 

 involves is so remote from mentality that ordinarily we 

 cannot sense it at all, let alone voluntarily initiate or arrest 

 it. The swallow is thus a reaction which, dealing with an 

 object (food) which has formed the aim and goal of a whole 

 train of mentally operated and supervised acts involving 

 the central nervous organs, finally takes the object thus 

 acquired and dismisses it abruptly from all commerce 

 with mind. Although within the body, it will under normal 

 circumstances never again come within the ambit of cogni- 

 zance of the mental organs. A dog comes to the platter, 

 and seizes the food; or in the case of man, he serves himself 

 with his hand and some tool to pass the food to his mouth. 

 Experiment shows that this stage of the act is impossible 

 to the dog after destruction of that part of the brain, the 

 cortex cerebri, which is the mental organ; similarly with man 

 where lesions (e.g. tumors) of the cerebral hemispheres may, 

 if extensive, cause a state of apraxia in which the individual, 

 though unparalyzed, is quite unable to feed himself or to 

 do so simple an act as to strike a match. A further phase 

 in the chain of nervous reactions associated with feeding 

 is the treatment of the food within the mouth by tongue 

 and teeth, its mastication and its mixing with saliva. Experi- 

 ment teaches that after removal of the whole "mental organ" 

 these processes still occur. This, as a preliminary act to the 

 swallow, an elaborately adjusted movement which transfers 

 the food from the mouth across the entrance to the windpipe 



