REGENERATION OF PROPORTIONATE 

 STRUCTURES IN STENTOR. 



T. II. MORGAN. 



THE important results of Gruber and of Balbiani on the 

 power of regeneration of pieces of Stcntor cocruleus opened 

 the way for further experiments; and the works of Johnson and 

 of Lillie on the same form have added some further results of 

 interest. There remained, however, one problem that had not 

 been touched upon by these investigators, an answer to which 

 is needed to make more complete our knowledge of the regen- 

 eration of unicellular forms. I refer to the question of the 

 proportionate development of the new organs in pieces of 

 different sizes, and from different parts of the body; and also 

 the no less important question of the change in size of old 

 organs that may be present on the piece at the time of its 

 removal. It is the purpose of the present communication to 

 describe certain experiments that bear on these questions. 



Although it is evident, in a general way, from the figures 

 given by Gruber and by Balbiani that a small piece produces a 

 smaller peristome than does a large piece, yet their figures do 

 not show definitely that such is the case, and, in fact, it would 

 be difficult to determine that such is the case from observa- 

 tions made on the swimming animals. The figures that have 

 so far been published represent the new stentor as it appears 

 while contracted or when swimming. To obtain sufficiently 

 accurate data for the problems that I wished to examine, it was 

 necessary to make the measurements and drawings from the 

 stentor at rest when in a fully expanded condition. The 

 object of my work was to find an answer to the following 

 questions : i . Do small pieces produce a new organism having 

 the typical proportions of the normal; and does it make any 

 difference in this respect as to the part of the stentor from 

 which the piece is taken ? 2. If a piece containing the old 



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