No. 641] 



THE RATE OF GROWTH 



545 



discussed. From the time at which an adequate diet was 

 supplied, until about the 432d day, the growth is ex- 

 pressed by the equation 



log 220 — 3; =-0193 (i — 363). 



This indicates a cycle of growth which was completed 

 at a body weight of 220 g. and which overlapped slightly 



360-432 was' calculated from log [i'/(220— a;) ] = .0193 (f— 36^).^ The weight 

 for days 433-600 was calculated from log [ (x— 220)/(288— a;) ] = .OO&l (t— 475). 



the second cycle of growth which was completed when a 

 body weight of 288 g. had been attained. The equation 

 representing the second cycle of growth is 



log • =-0091 (i — 475). 



The second eycl(' may lie represented by a curve having 

 ordinate and al)seissa axes originating at y = 220 and 

 a: = 432. The values are shown in Fig. 3. The agreement 

 between calculated and observed values is as good as 

 could be expected with only one animal in the sample. 



The next case to be noted is that of a male rat 

 (No. 2161) which was stunted l)y a dii't of inadequate 

 protein from age 38 days to auc 24S days." During this 



9 Osborne, T. B., and Mendel, L. B., J„ur. Jli,,!. Ou m.. 23 : 439-454, 1915. 



