486 G. N. CALKINS AND L. H. GREGORY 



« 



In the J, B, and E' series the pure lines dealt with represent 

 the first 32 cells of an ex-conjugant; the O and P series deal with 

 pure lines from only two quadrants in the 32 cell stage the progeny 

 from the other two quadrants having died, the series G, H', L, 

 M, Q, and T' deal with pure lines from the 4-cell stage on. As 

 the conditions thus are somewhat different in the different series 

 we shall consider them separately. 



A. Conjugations in the J series 



The first conjugation tests made with the 24 pure lines of this 

 series were exogamous tests made with 50 individuals from the 

 pure lines, and 50 individuals from a pure ex-con jugant culture, 

 known as no. 34' The mixtures were made October 22. No con- 

 jugations resulted, probably because of the small numbers used. 

 Similar mixtures with pure culture no, 74', likewise from one ex- 

 conjugant, were made on October 28. No conjugations resulted. 

 Another set was made with pure culture no. 41 on November 1. 

 No conjugations resulted. These mixtures were watched in each 

 case for from ten to twenty days. A fourth set of mixtures was 

 made with pure culture no. 29 on November 6 and a small num- 

 ber of pairs (4) were found in the mixture containing J 8. It was 

 evident from these initial tests that the numbers employed were 

 not large enough to furnish evidence of the conjugating power of 

 the different lines. Furthermore, it was seen that when conju- 

 gations did occur it was impossible to determine whether the 

 unions were paedogainous or exogamous — the size differences 

 fu- nishing no clue — although control tests were made at the same 

 time with individuals from the pure cultures in each case. From 

 this time on therefore we confined our observations to paedoga- 

 mous tests alone, Calkins ('02) and Jennings ('10) having shown 

 that paedogamous conjugations are just as effective as exogamous. 



The first paedogamous test of the 24 lines was made November 

 19, an equal number (as nearly as possible where thousands are 

 dealt with) were taken from the rich cultures and placed in Syra- 

 cuse dishes. Thirty pairs were counted in the J 1 line and 100 

 pairs in the J 21 line and not a single pair in the other twenty- two 



