352 FIELDS AND GRADIENTS IN NORMAL ONTOGENY 



fields, which, if the expression may be permitted, have not yet cut 

 their coats, but will do so according to their cloth. It will thus be 

 apparent that when organisms regulate, they do so for reasons 

 which are the same as those responsible for normal development, 



Fig. 170 

 Cyclopia in one member of a pair of anterior-doubled monsters in Triton. The 

 result of oblique constriction of the egg, and exclusion of the animal-pole region 

 from the half that will give rise to the cyclopic member. (From Spemann, Zool. 

 Jahrh. Siippl. vii, 1904-) 



and the facts call for no transcendent regulative principle such as 

 is invoked by Driesch in his theory of entelechies. The problem of 

 regulation is identical with that of certain important phases of 

 normal development. 



