REPRODUCTION OF THE HYPOTRICHOUS INFUSORIA 63 



with a high magnification in order to determine if the conjugating 

 animals were of normal appearance. The few pairs that did not 

 appear normal were rejected and are not included in the totals giv- 

 en above. Of the 152 pairs of conjugants isolated, between 25 and 

 30 pairs were used in making permanent preparations so that ap- 

 proximately 125 pairs remained for observation. The work of 

 isolation in both the epidemics of conjugation was carried on 

 throughout the time that the phenomenon was occurring and the 

 conjugating pairs were also isolated when the animals had been 

 united for varying periods of time. 



Careful study of the living conjugants entirely failed to reveal 

 any evidence pointing to a pathological condition of the gametes at 

 the time of conjugation. In neither shape nor size could any devi- 

 ation from the normal be observed. It could be noted in some cases 

 that the animals on a slide in which conjugation was occurring 

 evinced remarkable activity. Calkins ('02a) found with Paramae- 

 cium caudatum that at such periods the protoplasm of the animals 

 became 'miscible' and that as many as eight or ten individuals 

 would be found fused together in an irregular mass at times. Al- 

 though it was very evident that conjugation would occur during 

 these epidemics whenever opportunity was afforded, abnormal 

 fusions of several animals were never observed. 



Maupas ('89) gives the length of time during which the gametes 

 of S. pustulata are together in conjugation as varying from twenty- 

 two to thirty-nine hours according to the temperature; the shorter 

 periods occurring with the higher temperatures. In this work 

 the period was found to vary from twenty-four to thirty-six hours, 

 thus corresponding very closely with the time given by Maupas. 

 A very few cases were noted in which the animals had not separ- 

 ated at the end of thirty-six hours but it was clearly evident in 

 such cases that the process was not normal and the resulting ex- 

 conjugants never gave any promise of continued life. The records 

 show that from over 90 per cent of the conjugating animals ex- 

 conjugants were obtained which were at the time of separation, as 

 far as could be judged from a careful and exhaustive study of the 

 living material, normal in every respect and which gave every 

 promise of continued life and multiplication. In brief, then, and 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY. VOL. 1.3, NO. 1 



