EFFECT OF CONJUGATION 



301 



TABLE 9 



Experiment 3. Paramecium caudalum. Relative number of fissions for the con- 

 juganis and non-con jug ants: during the four days, June 20 to June 24, 1909. {In- 

 cluding only those that lived throughout the four days.) 



Number of conjugant lines. 



Number of non-eonjugant 



lines 



6.222 



10.813 



ment. The temperature during the four days that the experi- 

 ment lasted was excessively high, the thermometer standing 

 much of the time above 90° F, (above 32°C.)- The non-conju- 

 gants multiplied with furious rapidity, at the rate of two to four 

 fissions a day (one fission in 6 to 12 hours), so that the average 

 for all that lived through was a little over two and a half per day 

 (one fission in 9f hours). The conjugants, on the other hand, 

 multiplied much less rapidly, the rate being but one-and-a-half 

 per day, or one fission in eighteen hours. 



Correlative with this excessively rapid rate of reproduction, 

 the non-conjugants showed a very high mortality. At the end 

 of four days, 35 of the original 51 lines were dead, so that the 

 mortality was 68.6 per cent. In the conjugants, on the other 

 hand, of the original 47 lines, only 11 died, or but 23.4 per cent. 



The data for the rate of fission of the conjugants and non-con- 

 jugants in this experiment are given in table 9. 



The results of this experiment agree with those of all the others 

 in showing that conjugation decreases the rate of fission. They 

 differ from those of all others in the fact that the mortality is 

 much greater in the non-conjugants. The result, due, as it 

 evidently is, to the excessive rate of fission induced in the non- 

 conjugants by the very high temperature, shows that under 

 certain conditions conjugation may have a directly protective 

 effect, owing to its decreasing the rate of multiplication. Inter- 

 esting results would be obtained by comparing conjugants and 

 non-conjugants of the same stock under diverse conditions; 

 high and low temperatures, different chemical conditions, et 



