76 CM. JACKSON 



investigations of Donaldson, Hatai, Jackson, Lowrey and others, 

 considerable progress has been made toward the establishment of 

 a growth norm for the albino rat. Since the normal growth proc- 

 ess and the relative weights of the organs are frequently modified 

 by malnutrition from A^arious (sometimes unsuspected) causes, it is 

 clearly of gr^at importance to know the effects produced by in- 

 anition. In drawing conclusions from the results of any experi- 

 ment upon animals, the possible effect of inanition should always 

 be kept in mind. The present investigation upon this subject, 

 which was begun at the University of Missouri, has been con- 

 tinued at the University of Minnesota with the aid of a special 

 grant from the research fund of the Graduate School. The 

 grant was used to employ a research assistant, who cared for 

 the animals and assisted in the dissections, weighings, calcu- 

 lations, etc. 



MATERIAL AND METHODS 



The material included 21 well-nourished adult albino rats 

 (Mus Norvegicus albinus) of unknown age. Two of these (O 5 

 and O 6) were derived from the Missouri colony and 19 from a 

 local Minnesota stock. Of the 21, 4 were females and 17 males. 

 They had been fed chiefly upon grain (oats and corn) with occa- 

 sional meat and vegetables, and were placed upon a bread and 

 milk diet for some days before beginning the experiment. Dur- 

 ing the experiment they were kept in cages with wire-net bot- 

 toms, allowing the feces (which might otherwise be eaten) to drop 

 through. 



Fifteen of the rats were used for the acute inanition experi- 

 ment. They were allowed plenty of water, but no food other- 

 wise. They were weighed daily and the individual records kept. 

 The initial body weights varied from 182 to 367 grams (table 3). 

 They were killed after 6 to 12 (average 9) days,^ the total loss 

 in body weight varying from 25 to 39 per cent (average loss, 



^ Bell ('11) found that the wild brown (Norway?) rat in captivity would live 

 only 3 or 4 days, with loss of 25 or 30 per cent in body weight, when water is 

 supplied but food withheld. Among animals in general, the older or larger are 

 able to withstand inanition longer than the younger or smaller animals, probably 

 on account of less rapid metabolism in the former. 



