62 GEORGE ALFRED BAITSELL 



Abnormal animals had never occurred in any of the cultures kept 

 on the beef mediu^n previous to conjugation and in the culture kept 

 on the hay infusion medium, in which no conjugation occurred during 

 its entire history, entire freedom from abnormal and degenerate ani- 

 7?ials was noted. In figures 7 and 8 are shown two typical specimens 

 from thie hay culture. Figure 7 represents a characteristic speci- 

 men preserved at the time of the first epidemic of conjugation in 

 the Sb culture, and figure 8 shows an animal preserved shortly be- 

 fore the death of the hay culture. In this last figure one of the 

 micronuclei is seen in the stage of division. The other micro- 

 nucleus is present and in the same stage, but is out of focus. 



From the study of the living material it has been shown that the 

 non-conjugating animals of the Sb and Sbhb cultures kept on the 

 beef extract medium, coincident with the appearance of conjuga- 

 tion, began to degenerate and die. The prepared material gives 

 proof that the degeneration resulted in marked morphological 

 changes in both the nuclear and cytoplasmic structure. 



V. MORPHOLOGY AND PHYSIOLOGY OF THE CONJUGANTS 



A. Living material 



In order to trace the effect of conjugation on the ex-conjugants, 

 it was deemed necessary to isolate a large number of the conjuga- 

 ting animals. Accordingly, during the first epidemic, 132 pairs of 

 conjugants were isolated, and in the second epidemic 20 more pairs 

 were added, making in all 152 pairs which were isolated. More 

 conjugants would have been isolated in the second epidemic but 

 owing to the scarcity of the material it was impossible. Each pair 

 of conjugants was drawn up with a fine pipet and then transferred 

 to a sterile depression slide and about five drops of the beef extract 

 medium added. Inasmuch as this was exactly the same kind of 

 wec^mm in which the animals had been kept previously and in which 

 the conjugation had occurred, the character of their environment 

 was not changed by the isolation. Consequently the possibility of 

 any reaction of the conjugants due to the change of environment 

 was entirely eliminated. Mention should also be made of the fact 

 that, at the time of isolation, each pair of conjugantsw^as examined 



