154 CM. JACKSON 



balls, spinal cord, alimentary canal (both empty and including 

 contents), testes, hypophysis and suprarenal glands. The 

 suprarenals undergo sexual differentiation in weight (as occurs 

 normally), but the hypophysis apparently does not. 



(2) There is no marked change in the weights of the brain, 

 heart, kidneys and epididymi. The liver is variable, showing a 

 definite increase in the earlier periods, but a decrease later. The 

 lungs show a slight decrease in the early periods, but not in 

 later. 



(3) There is a well-marked decrease in the weights of the 

 thymus ('hunger involution'), spleen, thyroid gland and ovaries. 



When the organs are similarly grouped according to degree of 

 loss during chronic inanition in the adult (slight loss, loss pro- 

 portional to body, and loss greater than body) , many differences 

 are found on comparison with the corresponding groups in the 

 young during constant body-weight. This is explained as due to 

 to the presence of both the growth tendency and the (more or 

 less different) maintenance tendency in the young animals, 

 whereas in the adult there is only the tendency to maintenance. 

 Both the growth tendency and the maintenance tendency, 

 however, show characteristic differences in the various organs 

 according to nutritional conditions (normal nutrition, acute or 

 chronic inanition). 



