I. NEURULATION 127 



If Dalcq's hypothesis proves correct, new problems will arise 

 at once. The phenomenon that the material of the germ can 

 react to quantitatively different organisine concentrations by 

 qualitatively divergent differentiation awaits further analysis. 

 In this way new riddles, setting new tasks to science, are 

 brought to light with each new problem solved. 



