RECONSTITUTIONAL PATTERNS IN EXPERIMENT 417 



on the upper surface is evidently determined by the contact-free-surface 

 differential. Localization of any one of the multiple axes appears to be 

 fortuitous but probably results from localization of regions of greater 

 cell activity after return to water. With disappearance of the entodermal 



Fig. 142, A~I. — Determination of new pattern in Corymorpha pieces by the contact-free- 

 surface differential after decrease or obliteration of the original polarity by differential in- 

 hibition. A-C, ethyl alcohol 2 per cent for 48 hr. following section, development in water; D, 

 ethyl ether 0.25 per cent for 26 hr. preceding section, five new a.xes from upper side after return 

 to water; E, chloretone 0.02 per cent for 26 hr. following section; F-I, dorsiventrality deter- 

 mined by the contact-free-surface differential after slight inhibition (from Child, 1927(2). 



canals their cells tend to accumulate irregularly in small groups, and 

 there is some evidence that these cell groups just beneath the ectoderm 

 may play a part in localizing the new axes. 



Short pieces lying on one side with httle or no movement or change in 

 position in well-aerated standing water and without preceding inhibition 



