BIPiiRENTAL INHERITANCE IN PARAMECIUM 451 



of the present experiment, is evidently too small to account for 

 the very marked coefficients found when conjugation has actually 

 occurred. While assortative mating may account for a very 

 small degree of similarity between the members of pairs, the pro- 

 cess of conjugation itself results in a marked increase of that 

 similarity. 



That is, the two members of a pair are more alike in their herit- 

 able characters after conjugation than before. As a result, their 

 progeny resemble each other in fission rate more than they would 

 have done if conjugation had not occurred. Conjugation results 

 in biparental inheritance. 



We shall see the demonstration of this conclusion completed 

 by the results of Experiment 15, to be described in Part III. 



PART III 



H. S. JENNINGS 

 CONJUGATION WITHIN A PURE STRAIN! EXPERIMENT 15 



The results thus far given require to complete them a study 

 of biparental inheritance in the case of conjugation within a 

 pure strain, where all the conjugants are derived by fission from 

 a single individual. Such an experiment, including both pairs 

 and split pairs, was carried through in August and September, 

 1912. This experiment has been described in my paper on 

 the Effect of Conjugation (this Journal, 1913, vol. 14, page 343), 

 and the records of the experiment are given in full in tables 34 and 

 35, in the Appendix of that paper. The results bearing on bipa- 

 rental inheritance, to be given here, are drawn from analysis of 

 the data given in the tables just mentioned. We shall refer to the 

 experiment as Experiment 15, in accordance with the designation 

 used in the former paper, but it was carried through subsequent 

 to Experiments 16 and 17 of the present paper. 



Referring the reader then to the paper just cited for a descrip- 

 tion of the experiment and the detailed record, I shall here men- 

 tion only essential points. In this experiment 88 fines derived 

 from ex-conjugant members of })aii-s, and 174 lines derived from 



