EFFECTS OF THIRST — ALBINO RATS 415 



per cent in body weight. Bowin ('80) also noted in rabbits an 

 absolute decrease (but relative increase) of weight in the heart 

 during thirst, Tobler ('10) obtained variable results (+4.1 to 

 — 21.5 per cent) in the weight of heart and lungs together in dogs 

 subjected to experimental diarrhea with loss of 22.4 to 29.8 per 

 cent in body weight. 



After inanition of albino rats with water, Jackson ('15) like- 

 wise noted that the loss of weight in the heart is somewhat less 

 than that in the body as a whole. He cites data from several 

 previous observers showing similar results in various animals. 

 An atrophy of the heart in pigeons and monkeys on vitamine- 

 deficient diets has recently been observed by McCarrison ('19). 



Aorta. The aorta was cut anteriorly at its junction with the 

 heart and posteriorly at its bifurcation. All the branches of the 

 aorta were clipped close to the vessel, and the surrounding fat tis- 

 sue and lymphatic nodules were removed. The blood was re- 

 moved from the aorta, and the vessel was weighed in two controls, 

 two test rats in acute-thirst, and seven in chronic-thirst experi- 

 ments (table 1). 



The aorta in the acute-thirst rats apparently decreased in 

 average weight 42.5 per cent and in the chronic-thirst 44.6 per 

 cent. While the number of observations (in the controls and 

 the chronic tests) is too small to be very significant, the results 

 indicate that the loss in the weight of the peripheral arteries may 

 be fully as great as that of the heart. 



Spleen 



The spleen at autopsy usually appeared small and atrophic. 

 The capsule is sometimes thickened. Upon section, the pulp 

 appeared relatively pale brownish, and the trabeculae more 

 prominent than in the normal organ. The spleen in the acute- 

 thirst series (table 2) shows a loss of 66 per cent in average 

 weight and in the chronic-thirst series a loss of 73.3 per cent. In 

 the rat (Si. 2), after total inanition, the corresponding apparent 

 loss in the weight of the spleen is 62.9 per cent. As seen from 

 table 1, the weight of the spleen, even in normal rats, is exceed- 



