EFFECTS OF THIRST ALBINO RATS 



451 



SPLEEN 



The spleen (table 2) shows a marked loss in average weight 

 (36.6 to 48.4 per cent) in all the test groups but one, in which the 

 loss appears much smaller (9.1 per cent). The very small appar- 

 ent loss in this test group is due to an abnormally large spleen 

 which weighed 0.2 gram, which brought up the average for the 

 group. If this abnormal spleen were excluded, the loss in this 

 group would appear as 46.5 per cent. Similarly in the last group, 

 the inclusion of an abnormally large spleen gives an apparent 

 average increase of 36.6 per cent; omitting this spleen, there is an 

 average loss of 37.6 per cent. Although the spleen is normally 

 one of the most variable organs in the body (Jackson, '13), requir- 

 ing caution in drawing conclusions, it is evident that it usually 

 undergoes a great loss in weight in young rats held at constant 

 body weight by thirst. 



In adult albino rats during thirst, both acute and chronic, 

 the spleen similarly loses relatively much more in weight than does 

 the body as a whole (Kudo, '21). Jackson ('15 a) found that in 

 young rats held at maintenance by underfeeding beginning at the 

 age of three weeks there is a marked tendency to decrease in 

 weight of the spleen, while at later (and longer) periods the spleen 

 appears to undergo no material change in weight. In the under- 

 fed newborn rats, Stewart ('19) found an increase of 33 per cent 

 in the spleen. 



