Regeneration 181 



lost part of the Ascidian. If an interstitial tissue is 

 digested it becomes a question of how much of this tissue 

 undergoes hydrolysis. If there is little destroyed the 

 old shape of the gills remains, if too much is digested 

 the old gills become a shapeless mass in which a certain 

 number of the old cells are maintained and give rise to 

 the new animal by cell division. The material for the 

 new organs must of course be furnished from old cells 

 which have been digested. 



If regeneration takes place in pieces which take up 

 no food the newly formed organs must originate from 

 material absorbed from cells of the animal which are 

 hydrolyzed and whose material serves as food for those 

 cells which grow. Very often this process of digestion 

 takes place without loss of the total form of the organ 

 and is overlooked by the pure morphologists. In 

 Campanularia also the process of collapse described 

 above is only apparent in a fraction of the cases as in 

 Driesch's observations on Clavellina. * It is also possible 

 that the red and yellow entoderm cells which gather at 

 the end where the new polyp forms furnish the material 

 which is utilized for the process of growth of the cells 

 from which the tentacles arise (with or without giving 

 off specific "hormones" besides). 



1 One author, Miss Thatcher, in trying to repeat these observations, 

 did not notice the total collapse of the tissues and concluded that my 

 observations must have been wrong. The writer is fairly certain that 

 his observations were correct. 



