242 EMBRYOLOGY 



of this book — that of working out the basic facts and principles governing 

 the process of differentiation. We pointed out that there is another set of 

 problems which accompany differentiation — the problems of growth. The 

 embryo is constantly increasing in size during differentiation, converting raw 

 materials into new protoplasm. These two processes of growth and differenti- 

 ation are very intimately connected, as we shall soon see. We have chosen to 

 separate them for purposes of clarity of analysis. With the next chapter we 

 shall begin a study of the problems of growth in the embryo. 



