PHYSIOLOGICAL VARIATIONS IN PARAMECIUM 491 



A second set of rich cultures was made February 21 and tests 

 were started February 24, 26, March 1 and March 3; 180 pairs 

 were obtained from B2; 2 pairs from B4; 1 from B15; 1 pair 

 from B17; one from B30; and 5 pairs from B32. B15 and 17 

 belong to quadrant A; B 2 and B 32 belong to quadrant C; and 

 B4 and B30 to quadrant D. 



A third set of rich cultures was started March 25 and conjuga- 

 tion tests were made March 27, 29 and 30, and 31 ; 73 pairs appeared 

 in Bl; 34 in B 15; 38 in B17, all in quadrant A. Four pairs 

 appeared in B 2; 11 in B 18, both from quadrant B. Eight pairs 

 appeared in B4; and 10 in B30, both from quadrant D. 



A fourth test in May gave no pairs at all, the entire series re- 

 maining sterile. Series B therefore is a relatively weak race in 

 respect to conjugation, epidemics never occurring. 



C. Conjugations in the E' series 



The E' series was started from an ex-conjugant from a wild 

 culture December 14, 1912, and 28 pure lines out of 32 were 

 kept in permanent cultures (diagram 5, p. 492). Thirteen of 

 these have since died leaving 15 lines distributed as follows: 2 

 from quadrant A, 4 from quadrant B, 6 from quadrant C, and 3 

 from quadrant D, 



Rich cultures were rnade January 9, twenty-seven days after 

 isolation of the ex-conjugant and three tests on January 15, 20 

 and 27 gave negative results in all 24 lines save one, alive at that 

 time. In one line, E'9, four pairs were found in the final test. 



Rich cultures were again made February 23 and tests started 

 on the 28th of April, 4th and 8th of March. These tests resulted 

 in 221 pairs in E'17, and 23 pairs in E'24 and none at all in 

 any of the other lines. A glance at diagram 5 shows that E'9 

 and E'17 are from quadrant A, and E'24 is from quadrant C. 



A third series of tests was started with rich cultures on March 

 27, one month later. Tests were made March 30, April 1 and 

 April 4, resulting in 18 pairs in E'17; and none in any of the 

 other 18 lines alive at that time. 



Here again, the conjugation power is feebly developed epi- 

 demics never occurring in the pure lines. 



