374 MAN --AN ADAPTIVE MECHANISM 



The Liver : Excision of the liver causes within a few 

 hours a rapid decline in muscular power and in heat 

 production until death. Before death the H-ion con- 

 centration of the blood increases rapidly. 



Testicles and Ovaries: Excision of the testicles and 

 ovaries, before adolescence, prevents the development 

 of the secondary sexual characteristics and prevents 

 sex reactions and procreation. 



Pancreas: Excision of the pancreas interferes with 

 sugar metabolism. 



Thymus: Excision of the thymus interferes with 

 the growth of the skeleton. 



Hypophysis: Excision of the hypophysis interferes 

 with growth and with sugar metabolism, while exces- 

 sive hypophyseal secretion causes excessive growth 

 (gigantism) . 



Parathyroids: Excision of these two tiny bodies 

 interferes with calcium metabolism and may cause 

 death by convulsion (Calcium tetanus). 



All these defects support a mechanistic conception. 



Want of Certain Chemical Elements 



The human mechanism may be modified not only 

 by the loss of some of its component parts but also by 

 depriving the body of certain food constituents. For 

 example, the exclusion of sodium chloride from the diet 

 soon causes death, and the removal by milling of vita- 

 min, a tiny element in the husks of rice, has caused the 

 death of multitudes of rice-eating people and is the 

 cause of the disease known as beri-beri. The adminis- 

 tration of this minute constituent of rice prevents and 

 cures beri-beri (Craemer). 



