EMBRYONIC GROWTH 



145 



We need not enter into a discussion of this point here, which 

 concerns the problem not of relative but of absolute growth. 

 In any case, the growth-constants thus arrived at will give us 

 some real measure of growth-rate ; and further, the relative 

 growth-constant, which he uses for comparative purposes, is 

 arrived at directly from the growth-quotient above discussed. 

 However, for our purpose we may stick chiefly to the growth- 



10 II 12 13 14 15 16 17 18 19 20 21 days 



arith-log paper so that the slopes of the curves is directly proportional to 



(see text) ; B, against actual age of embryo. The scales of weight for the 



both, denotes weight of embryo. 



In B, + denotes brain-weight (from 001 to 1-02 g.) ; + metanephros weight (from 00014 to 

 0-13 g.). The lens and the fore-limb originate nearly together, but the latter grows much faster. 

 The brain starts growth early and then grows more slowly than the whole embryo, the metanephros 

 starts late and throughout grows much faster than the embryo. 



IO 



