No. 641] 



THE RATE OF GROWTH 



555 



D. SUMMAEV 



1. The growth of white rats during the first year shows, 

 two cycles, and each cycle follows the course of an auto- 

 catalytic reaction. The first cycle covers the period in 

 which the skeleton rapidly increases in size; the second 

 covers the period in which there is a production and depo- 

 sition of fat. 



2. The equations for the growth of the two sexes differ 

 in their constants, but each expresses the course of an 

 autocatalytic reaction. 



3. The earlier period of stunting did not prevent the 

 animals from attaining the full weight characteristic of 

 their sex after having an adequate diet. An equivalent 

 gain in weight was made more quickly in the animals re- 

 covering from suppression than in animals on adequate 

 diet. 



In other words the animals grew somewhat more rap- 

 idly during their period of recovery. 



4. The growth of white rats recovering from a long 

 period of suppression follows the curve of autocatalysis, 

 though a portion of the first cycle has been run during 

 the long period of suppi cssif*!!. 



5. The differeiiti.-il r. |u;it ions expressing the growth 

 rates show that the t\v(» .•>cl('< overlap to some extent. 

 The sums of the ovi rlaiininu' n mIiics ai)])roximate closely 

 the observed increnieMts. The second eyi-le of growth of 

 rats recovering from starvation l)egan and reached its 

 maximum relatively earlier than in the case of rats on 

 adequate diet. 



6. There is evidence for the idea that each cycle of 

 growth in this case had its specific catalyst and that the 

 potential activity of the catalyst was not impaired by 

 long periods of inadequate nutrition. 



