76 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES. 



Normal growth, as judged by curve of increase in body-weight, 

 was resumed on a diet consisting of 



per cent. 



"Trumilk" 60.0 



Starch 16.7 



Lard 23.3 



Similar experiences are shown after feeding gliadin (Charts 

 XCIX, C) or edestin (Chart LXV). 



In the case of rat 37 (Chart XCVII), a stunting period of 49 

 days on a diet of gliadin food for 37 days, followed by casein food mix- 

 ture for 12 days, was followed by normal resumption of growth under 

 a dietary regime in which a period of feeding on the above milk-food 

 was alternated with mixed food. Judging by the typical character 

 of the curve of growth in this animal the two types of resuscitation 

 diet, though radically different in origin, are equally efficacious in 

 promoting growth. The growth curve shows little deviation from its 

 usual course incidental to the changes in the dietary. 



It may be remarked that the early stunting does not neces- 

 sarily impair the capacity to breed at a later period when growth is 

 again established. Furthermore, we have found that the milk-fat- 

 starch mixture continued from early life in no wise impairs the 

 potency of rats as breeders. Its nutritive efficiency will be referred 

 to again. 



Experiments such as those recorded above give unmistakable 

 evidence of the fact that a considerable period of stunting by no 

 means impairs the " Wachstumstrieb " of these animals. As soon 

 as an appropriate diet is instituted growth begins anew and proceeds 

 with practically the same speed as under normal conditions. By this 

 we mean that a definite increment of gain from some fixed weight 

 requires approximately the same period for its accomplishment as in 

 the case of uninterrupted growth. A rat which will ordinarily grow 

 from 60 grams to 180 grams in body- weight in 60 days will make the 

 same gain even when its growth has been inhibited days or even weeks 

 and its size and form retained at a maintenance level. This will be 

 apparent by comparing, for example, the normal growth curve for 

 both male and female rats with that of the realimented rats, during 

 the same period of time, in Charts CXXII and CXXIII. 



It should be emphasized that the situation is here quite differ- 

 ent from that developed by Waters and Aron in the experiments 

 on cattle and dogs. With their conditions of underfeeding the animals 

 increase in size (height, etc.) while starving; and during the earlier 

 period of such trials a poorly fed animal may actually gain in height 

 as rapidly as a highly nourished one, fed to the limit of its appetite.* 



*Cf. Waters: The capacity of animals to grow under adverse conditions. Proceedings 

 Society for the Promotion of Agricultural Science, 1908, xxix, p. 15. 



