PHYSIOLOGICAL VARIATIONS IN PARAMECIUM * 489 



pairs, J 7, with 2022 pairs, J 8, with 3776 pairs, and J 21, with 

 2177 pairs. In addition to these usual findings 3 conjugating 

 pairs were found in line 15 (from quadrant C) ; 244 pairs in line 

 16, 15 pairs from line 17, and 16 pairs from line 20 (all three from 

 quadrant B), and 2 pairs were found in line 25 (from quadrant 

 D). Thus five of the fonner nineteen non-conjugating lines have 

 begun to conjugate after nine months of sterility. The conjugat- 

 ing power is apparently weak however, as shown by the small 

 numbers of pairs contrasted with the epidemics in lines, 1, 7, 8 

 and 21. The remaining fourteen lines gave no evidence at all 

 of conjugating. 



A second April test of the J series was made two weeks later 

 to see if the above result would be confirmed. The rich cultures 

 were seeded April 17 and conjugation tests were made on the 

 21st and the 24th resulting in 2810 pairs in Jl, 549 pairs in J 7, 

 1155 pairs in J 8, and 841 pairs in J 21, the usual numbers (two 

 tests only) for quadrant A. In quadrant B there were 824 pairs 

 in line 16, 39 pairs in line 17, and 2 pairs in line 20. In quadrant 

 D there were two pairs from line 25, 2 from line 29, and 2 from 

 line 30. In quadrant C there were no pairs at this time. The 

 first April test was thus confirmed with the exceptions that no 

 conjugations occurred in line 15 (quadrant C) and 2 pairs were 

 found in each of lines 29 and 30 (quadrant D) in which no pairs 

 had previously been found. 



With these tests the number of non-conjugating lines is re- 

 duced from 19 to 12 and the number of conjugating lines raised 

 from 4 to 11 although the conjugating power of the latter seven 

 lines is much weaker than that of the original four. All four 

 quadrants are now represented in the conjugating lines indicat- 

 ing that the power to conjugate is not a matter of nuclear factors 

 which can be shuffled about like specific Mendelian characteristics. 



Evidences of physiological weakness are now (May) beginning 

 to manifest themselves in the conjugating lines. This is shown 

 relatively, by the number of pathological divisions observed in 

 the Syracuse dishes. In April 420 pathological divisions were 

 counted in one Syracuse dish containing representatives of Jl 

 in which 1349 pairs had been counted. In J 21 during the same 



