AN AMICRONUCLEATE OXYTRICHA. II 131 



heritance of abnormalities occurring after conjugation in Para- 

 mecium caudatum, described many types of constantly recur- 

 ring abnormalities, among others were noted certain types of 

 double forms, arising on account of ^arrests in development,' 

 which invariably died in a short time. The same author de- 

 scribed a certain class of conjugants which never separated but 

 died while united. 



The preceding account deals with double or multiple forms 

 arising from one individual. Cases of long-continued plastogamy 

 in the ciliates are rare and are limited to fragmentary observa- 

 tions on compound organisms formed when three or more indi- 

 viduals attempt to conjugate. Engelman stated that these indi- 

 viduals could grow and multiply, while Maupas believed such 

 fusions had nothing to do with conjugation, but resulted in 

 monstrous formations which underwent incomplete and irregu- 

 lar divisions. Doflein ('07) described 'agamic fusions' of two 

 individuals in Paramecium putrinum and Stylonychia mytilus, in 

 which cytoplasm and nuclei of each animal fused to give an ap- 

 parently normal but relatively very large individual. Doflein 

 ('09) states further that as a rule plastogamic individuals did not 

 long remain united, but separated after a longer or shorter time. 



2. MATERIAL AND METHODS 



The ancestors of all animals described in these experiments 

 were descendants of stock animals of the culture (A) of a race 

 of Oxytricha hymenostoma. (See 'An Experimental Study of 

 an Amicronucleate Oxytricha,' part I). 



A full description is given in part I of the methods used in car- 

 rying on the daily isolation cultures, the preparation of the cul- 

 ture medium, the method of plotting the curves, etc. As the 

 methods used in this part of the study are the same, the reader 

 is referred to the previous paper for these details. 



