602 ROBERT SCHARFF. 



animals I had under observation all completed the act of fisssi- 

 parous reproduction within forty-eight hours. 



Comparing the division of Ct. monostylos (fig. 4, a — c) 

 with that of the two forms I just described, the most striking 

 difference lies in the fact that there is no appearance of buds. 

 In Ct. monostylos we have merely a breaking up of the 

 animal into two almost equal parts, each of which may again 

 break up into two or more parts. The regeneration only takes 

 place after the division has been completed. 



Summing up the result of Zeppelin^s researches on the 

 division of Ct. monostylos into a few words, we should have 

 the following : 



In the fully-grown normal individuals a constriction takes 

 place about the middle of the body, which gradually becomes 

 deeper and deeper. At the same time the intestine becomes 

 rounded off in the two parts, and ultimately the mother animal 

 breaks up into two daughter animals of about the same size, 

 one of which bears the head along with some segments, the 

 other the anus, also with a few body segments. The regenera- 

 tion always begins after division has taken place. 



Both daughter animals are capable of subdivision into parts, 

 all of which contain a portion of the original animals intestine. 

 Those parts are either — 



(1) Parts which have neither head nor anus, consist only of 

 one to three segments, and are incapable of division ; or 



(2) Parts without head or anus, possessing more than three 

 segments, which may divide again. 



The daughter animal which contains the primary head has 

 been noticed to constrict off a part provided with the secondary 

 anus. Whether a corresponding constriction also takes place 

 in the other daughter animal has not been observed. 



This constitutes the main difference in the mode of fissiparous 

 reproduction of Ct. monostylos, on the one hand, and 

 Ct. pardalis and parvulus on the other. 



