EFFECTS OF THIRST ALBINO RATS 441 



Percentage losses in the various organs were calculated as fol- 

 lows. The average weight (table 2) for each organ or part in the test 

 rats was compared with the corresponding average for the normal 

 controls of similar body weight. The data in the column 'Differ- 

 ence' express the apparent percentage changes (+ or — ) as the 

 result of the experiment. In table 2 the average gross body- 

 weight and net body weight (gross body weight minus intestinal 

 contents) are seen to differ but slightly (usually less than 5 per 

 cent) in the various test groups, as compared with the normal 

 controls. These differences have been ignored in calculating the 

 percentage changes for the various parts. 



In view of the comparatively small number of observations 

 and the known variability, especially of some of the organs (Jack- 

 son, '13), the conclusions reached in the present paper are by no 

 means to be considered as final. It is believed, however, that 

 they are sufficient to give an approximate idea of some of the 

 more obvious and important changes, so as to make possible a 

 comparison of the effects of a relatively dry diet (water deficiency) 

 with other forms of inanition. 



GENERAL OBSERVATIONS 



In general the test rats remained active and apparently healthy, 

 although many died during the course of the experiment, as above 

 stated. The skin becomes somewhat roughened, but the hair 

 is not easily detached (as occurs in adults during thirst). Dry- 

 ness and desquamation were observed on the plantar surfaces. 

 The claws become much elongated, especially in the later test 

 periods. The fecal material is usually hard, never diarrheal in 

 character. The urine is scanty. Haemorrhage from the con- 

 junctiva or nose was not observed, although it sometimes occurred 

 in the stomach or intestines. In the rats dying during the experi- 

 ments (not included in the tables) hemorrhage and ulceration of 

 the stomach were often observed. Dryness of the external genital 

 organs, especially in females, was observed, and eczematous condi- 

 tions often occurred in the longer experiments. Paralysis of the 

 legs or other parts was never found in the young rats (as noted 

 occasionally in adults by Kudo, '21). In some young rats the 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 33, NO. 2 



