EFFECTS OF THIRST ALBINO RATS 449 



weight of the adult rats subjected to thirst showed no significant 

 change in weight (Kudo, '21). The constancy of the brain weight 

 in adults under various forms of inanition has been repeatedly 

 observed by numerous investigators. McCarrison ('19), how- 

 ever, finds an apparent increase of one-seventh in the brain 

 weight of monkeys on various diets deficient in vitamines. 



SPINAL CORD 



The spinal cord shows a marked and progressive increase 

 (20.8 to 53.1 per cent) in weight in the various test periods 

 (table 2). 



Jackson ('15 a) found an increase of 36 per cent in the spinal 

 cord of rats held at constant body weight by underfeeding from 

 three to ten weeks of age, and a smaller increase was obtained by 

 Donaldson ('11). In newborn rats, held at maintenance by 

 underfeeding from sixteen days, Stewart ('19) found an increase 

 of 83 per cent in the weight of the spinal cord. In the thirst 

 experiments on adult rats, the spinal cord shows but little change 

 in weight (Kudo, '21). 



SCIATIC NERVES 



The sciatic nerves (nn. ischiadici) in the test rats showed an 

 increase in weight which is similar to that of the spinal cord, 

 excepting the first period (table 2). This indicates that the 

 continued growth of the spinal cord is correlated with that of the 

 peripheral nerves, as might be expected. In the thirst experi- 

 ments on adult albino rats, however, the sciatic nerves lost in 

 weight, while the spinal cord did not. No further data on the 

 changes in weight of peripheral nerves during inanition have been 

 found in the literature. 



EYEBALLS 



The eyeballs likewise show a marked and progressive increase 

 in average weight during the various test periods (table 2) , vary- 

 ing from 9.3 to 70.8 per cent. The apparent increase of 70.8 per 

 cent in weight of the eyeballs during the thirst experiments is 

 greater than that observed in any other organ or system. 



