SECT. 3] 



AND ORGANISATION 



549 



Murray next showed that the curves for growth-rate of heart 

 tissue in explanted culture, obtained by himself working with Cohn 

 & Rosenthal (see p. 461), fell in the same way as those for the intact 

 embryo in its egg, but that the curve for latent period (see p. 462) 

 behaved, on the contrary, exactly like those for integration and 



Deo/35 



11 13 



Incubation age 



Fig- 93- 



chemical differentiation, rising very slowly at first, and thereafter 

 more rapidly. Thus chemical constitution, metabolic rate, and latent 

 period of explant growth are to be correlated and distinguished from 

 growth-rate both in the intact animal and in tissue culture. Fig. 93 

 shows the difference between growth-rate and metabolic rate, as 

 judged from the rate of carbon dioxide production. 



As a result of this analysis of embryonic development, at least five 



