SECT. 2] 



AND WEIGHT 



387 



and has no slackening off or self-inhibitory phase; the increment 

 curve is therefore singly sigmoid. But here, when the absolute 

 growth-curve is itself sigmoid, the increment curve is symmetrically 

 sigmoid, rising to a maximum and then falhng away again to zero 

 during the second phase. Finally, the corresponding Minot curve is 

 shown by the line joining the triangles, and, as usual, it declines 

 throughout growth from an initially very high value. 





n 70 



30 



«25 



n) 

 u 



CO 



a»20 

 m 



i. 



OU 



60 



<0 



2 40 



■^30 



0.20 



gms. 



200 



cent 

 day 



DaysO 10 20 30 40 50 60 70 80 90 100 HO 120 130 140 150 160 lyO^lB0 190 200 210 220 

 o 8 18 28 38 48 58 68 78 88 98 108 118 128138148 158 168 178 188198 



% I Age 



o 

 U 



Fig- 35- 



There are other ways, however, in which the subject of embryonic 

 growth-curves can be introduced. Ostwald's classical work on 

 growth in metazoa, which appeared in W. Roux's "Vortrage" 

 series in 1908, laid great emphasis on the value of knowing the 

 precise route through weight taken by an organism on its way 

 from egg-cell to finished embryo. In Fig. 36, taken from his mono- 

 graph, several different curves are shown relating time to weight. 

 At the time A, at hatching or birth, for instance, the weight of the 



25-2 



