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VI 



Nervous and Endocrine Control of the Body 



THE great development of the cerebrum in man is responsible, in a 

 large way, for man's preeminence over the lower forms of life. For 

 example, the periodic triumphs of the insects over man are not planned by 

 the insects. On the other hand, man's reasoning is enabling him to control 

 the bisects. 



It is, indeed, a long jump from the withdrawing from contact of its 

 pseudopodium by the simple, one-celled A?neba, a type of nervous re- 

 sponse, to the creative genius of an artist or the working out of a formula 

 by a physicist. Evolution means change and the nervous system has 

 evolved according to the same laws as other parts of man. Sometimes 

 evolution has taken peculiar turns. Witness the now-extinct dinosaur 

 who had two brains, one in his head and the other in his sacral region so 

 that he could make both head and tail of it. 



Concerning the brain, there are many types of untruths extant. One 

 is the false study known as phrenology by means of which one is sup- 

 posed to tell certain qualities of the brain by fingering the bumps on the 

 cranium. Some people believe too that the size of the brain is an indication 

 of the quality while others hold that the more convolutions one's cere- 

 brum has, the greater is one's thinking ability. Of course, these ideas are 

 no longer valid. 



The study of the ductless glands and their products is now one of the 

 most active fields in animal physiology. Malfunction of these important 

 structures is now known to cause certain types of diabetes, goitre, steriUty 

 and so on. Some of these products or hormones have been isolated and 

 purified sufficiently so that cures for certain conditions are possible. Hopes 

 run high at the present time for the use of hormones in a more sustained 

 attack upon human diseases and even upon abnormal behaviour. 



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