FACTORS IN EMBRYOGENESIS 39 



Experimental studies of apices have shown that lateral members 

 such as leaves and buds, and presumably roots, owe their characteristic 

 form and structure, among other considerations, to the positions in 

 which they are formed. That is to say, it is to the genie control and 

 mechanics of growth that we should look for an account for the 

 characteristic form and structure of organs and not to the presence in 

 the race of particular factors which specifically determine these organs. 



Lastly, it may be duly emphasised that, if progress is to be made, it 

 is not merely a question of working at apices, or embryos, from the 

 morphological, physiological and genetical points of view, and of 

 bringing the respective data together : a profound effort must be made 

 to effect an actual integration of these data; for only by so doing can 

 we hope to gain an adequate insight into the progressive organisation 

 which is characteristic of development both in the individual and in the 

 race. 



