EFFECT OF CONJUGATION 



331 



jugated among themselves; from these conjugants a single 

 ex-con jiigant was taken and allowed to multiply till there was 

 conjugation among these. A single member of a pair was again 

 allowed to propagate till there was conjugation; and thus the 

 process was repeated eight times, all the members of each of the 

 eight non-sexual series being the progeny of a single ex-conjugant 

 of the previous series. The known history of this race is illus- 

 trated in the diagram of figure 1. This diagram shows also the 

 relation of the organisms employed in the present experiment to 

 those used in previous experiment. They belong to branch B of 

 figure 1, and are derived from a single ex-conjugant of the conju- 

 gation of April 29; they are thus the same stock as the conjugants 

 employed in Experiment 9. 



Self-fertilization for eight generations in succession, of course 

 goes far in getting rid of heterozygotism in most characters. East 

 and Hayes ('12) have given the general formula for determining 

 what proportion of the organisms would be homozygotic with 

 respect to any given number of characters after a given number 

 of self-fertilizations; this being based on the formula originally 

 given by Mendel ('66). In a recent note, written before the 

 paper of East and Hayes had appeared, I went into some details 

 on the matter (Jennings '12). If we call x the proportion of the 

 organisms that will be homozygotic, letting n be the number of 

 successive self-fertilizations and m the number of pairs of char- 

 acters, then the formula for use is 



'2" - r 



X = 



2- 



From this formula we find that after eight successive self- 

 fertilizations the proportion of the organisms that would be 

 homozygotic for any one, two, or more characters, up to ten, is 

 as follows: 



