EFFECTS OF THIRST ALBINO RATS 445 



five periods gains of 5.7, 24.3, 20.0, 25.7, and 28.6 per cent, respec- 

 tively (table 2) . 



Thus the rats held at constant body weight by thirst become 

 relatively long-tailed, as found likewise by Jackson ('15 a) in 

 young rats held at maintenance by underfeeding. Some data 

 indicating an opposite result were reported by Hatai ('08). 



In adult rats during thirst the body length in the acute series 

 shows an average loss of 11.4 per cent and in the chronic-thirst 

 series a loss of 14.7 per cent. The tail, however, has nearly the 

 same average length in controls and test rats (Kudo, '21). 



INTEGUMENT 



The general changes in the integument were mentioned above 

 under 'General Observations.' In the young rats held at con- 

 stant body weight in five test series (table 2) there is a slight ap- 

 parent loss varying from 7.5 to 14 per cent in weight of the integu- 

 ment (which includes the skin and appendages, hair and claws). 

 It would appear that this slight loss occurs early, and is not pro- 

 gressive during the course of the experiment. 



In adult rats during thirst the loss of the integument is very 

 nearly proportional to that of the whole body (Kudo, '21). 



In inanition (with water) a much greater loss of 36 per cent or 

 more was found in the weight of the integument of young rats by 

 Jackson ('15 a). 



SKELETON 



The bones, together with the cartilages, periosteum, and liga- 

 ments, constitute the 'ligamentous skeleton.' The bones and 

 cartilages, after removal of the periosteum and ligaments by 

 immersion for about one hour in 1 per cent aqueous ' Gold Dust ' 

 (a commercial soap powder) solution at 90°C., constitute the 'car- 

 tilaginous skeleton.' Donaldson and Conrow ('19) have shown 

 that while such a maceration in hot 'Gold Dust' solution causes 

 only a slight loss (less than 5 per cent) in the skeleton of adult 

 rats, in young rats the loss in skeletal weight is considerably 

 greater, amounting to about 15 per cent in the new born. The 

 humerus and femur (of both sides) were therefore cleaned sepa- 



