NUTRITION AND GROWTH: I. 35 



more than two hundred days in an animal of from 2,000 to 2,200 grams 

 (dog A) which at first received 125, then 150, and later 170 calories, 

 whereas 190 to 200 calories were required according to the surface law. 



All these animals while receiving a considerably smaller quantity of 

 cnerg)- than that required' for maintenance, not only did not lose in body 

 weight, but in the initial part of the experiment increased slightly. 



The animals in the beginning of the experiment were well nourished 

 with a fair storage of fat in their tissues. The growth of such an animal 

 can not fully be stopped by restricting its food ; for if we gave it the full- 

 requirement for maintenance, certain parts of its body, especially the 

 skeleton, would undoubtedly gTOM-, thus increasing the weight of the 

 animal. If we wish to keep such an animal from increasing in weight, we 

 must starve it by giving so low a diet that the gain in weight, produced 

 by the increase of certain parts of the body as an effect of their growth, 

 is compensated by the loss in body substances used for maintenance in 

 addition to the insufficient amount of calories taken in the food. The con- 

 dition mentioned in the first lines of this paragi"aph is the one which we 

 encounter in dogs II, III, XIY, XI, YI, and A at the beginning of 

 the experiment. It is for this reason that we find such a great restric- 

 tion of food necessary in order to prevent an increase in body weight, 

 or to allow only a very slight one. In this period we are not able to 

 suppress the growth by restricting the food, and constancy of weight does 

 not indicate a cessation of growth. 



However, these conditions change the longer the time during which 

 this severe starvation lasts. If the greater part of the energy stored to 

 give the reserve forces to the body is consumed, the animal, without 

 losing in weight, becomes very mi;cli emaciated. If the low diet is 

 continued, the aniriial finally loses somewhat in weight, and soon dies in 

 a completely emaciated condition. This is simply because the animal 

 does not have much more to lose. This explains the course of the ex- 

 periments on dogs XIV and VI, in which case we could demonstrate 

 plainly an entire loss of all reserve stuffs (fat) and a severe destruction 

 of body proteins as well. 



If instead of continuing the low diet, which initially was necessary 

 to prevent an increase in weight, we follow it with sufficient food for 

 maintenance or nearly that amount, the animal not only will be prevented 

 from increasing in weight, but also from gi-owing. This case is realized 

 in experiment IV with dog A. In all probability, nearly all the reserve 

 stuffs, all stored energy, in this animal were used up during the first 

 period while the animal received only 110 calories, in the same manner 

 as with dogs V or XI, 'where the fact was demonstrated by analysis. 



We have seen by the foregoing considerations that, during the time of 

 starvation, a considerable fraction of the energy required for maintenance 

 is obtained from the energy stored in the body. However, this quantity 



