Studies on Regulation. IV. 



103 



If these views are correct it follows that these form-changes, at 

 least in the old parts, and often in the new as well, must occur 

 to a greater extent when regeneration is not quantitatively com- 

 plete, or must be more evident, since the growth of the 

 parts may mask it to a greater or less extent. This is actually 



.>-p 



Fig. 1. 

 the case, as Morgan's experiments have shown (Morgan, '00). 

 Since my primary object in investigating the regulative processes 

 in Leptoplana was the examination of the alterations in propor- 

 tion, the most favorable* conditions for this purpose, viz., absence 

 of food, were desirable. 



