EEPRODUCTION OF THE HYPOTRICHOUS INFUSORIA 67 



stages and no differences being noted between the ex-conjugants 

 which were experimented with and their mates which remained 

 in the same medium in which the separation had taken place. 

 A great many of the shdes were examined for cysts but none were 

 found. That nothing injurious to the ex-conjugants was present 

 upon the shdes or in the medium in which they had died was 

 shown several times by placing on the same slides and in the same 

 medium in which the ex-conjugants had died, individuals from the 

 stock of the culture. In every case they lived and divided. 



From the fact, as noted above, that the ex-conjugants pass 

 through certain degenerative stages and die within forty-eight 

 hours after separation, conclusive evidence is furnished of the in- 

 fertility of the conjugation which occurred in these cultures of S. 

 pustulata which were kept on a beef medium. 



B. Prepared material 



Passing next to a study of the permanent stained preparations 

 of the ex-conjugants, typical examples of which are shown in fig- 

 ures 13-15 it can be said that the micronuclei are present in all 

 cases. Figure 13 shows a condition shortly after separation. 

 Figure 14 represents an early stage in the degenerative processes, 

 and figure 15 shows very clearly the appearance of an ex-con ju- 

 gant during the last stage of this process. 



It is evident, then, that the study of the prepared material of 

 both the conjugants and the ex-conjugants shows that Maupas 

 was incorrect in his statement that infertility of conjugation, in 

 this form, is due to a loss of the micronuclei : and the results ob- 

 tained in this investigation agree with those obtained by other 

 investigators working on closely related species. 



Split conjugation 



Calkins (02a) in his work with paramaecia, was able to separate 

 the conjugants before the regular time and before there had been 

 any interchange of nuclear material. This was done by drawing 

 up the conjugating animals in a fine pipet and then ejecting them 

 somewhat forcibly. From the 'ex-conjugants' thus obtained he 



