CONJUGATION AND ENCYSTMENT 355 



died during the same periods. By referring to the table it will 

 be seen that a total of 400 individuals which had conjugated 

 were isolated and that 163, or 47.5 per cent of these died without 

 fission; that a total of 134 conjugating individuals in which 

 nuclear transfer was prevented were isolated and that 32, or 

 23.8 per cent, of these died without fission; that a total of 30 

 small individuals ready to conjugate were isolated and that 

 14, or 46.6 per cent of these died; and that a total of 41 large 

 individuals not ready to conjugate were isolated and that only 

 3, or 7.3 per cent of these died. 



These results show that the death-rate in the individuals not 

 ready to conjugate was very much lower than in those ready to 

 conjugate and they also show that the death-rate in the ex- 

 con jugants taken as a whole was considerably higher than it was 

 in the separated con jugants and those ready to conjugate. A 

 further study of the table shows, however, that conclusions 

 based on a consideration of the experiments taken as a whole are 

 misleading. This is due to the fact that in a nu,mber of ex- 

 periments in which only ex-conjugants were isolated, the death- 

 rate was on an average higher than in the others. It is obvious, 

 therefore, that these experiments should be omitted in the 

 calculations. When this is done it leaves a total of 200 ex- 

 conjugants of which only 34, or 17 per cent died without fission. 

 That is, 5.8 per cent less than the percentage of deaths in the 

 conjugants which were separated without nuclear interchange 

 and 26.9 per cent less than that in the small individuals ready to 

 conjugate. These experiments, therefore, indicate that conju- 

 gation produces a decrease rather than an increase in death-rate. 

 They indicate, however, that the preliminary steps in the process 

 of conjugation do cause an increase in death-rate, for in the 

 large specimens in which no preparation for conjugation had 

 occurred the death-rate was much lower than it was in those in 

 which such preparations had occurred. 



In the ex-conjugants and the small individuals ready to con- 

 jugate or separated immediately after conjugation the variation 

 in death-rate was very large. In some experiments all died, in 

 others none. In the large individuals not ready to conjugate 



