2 8 BOTANICAL GAZETTE Ljuly 



ana plants from the Fj of O. lataXO. Lamar ckiana (13), in which 

 sometimes eight chromosomes pass to one pole and six to the other; 

 but it may also occur rarely in the pure races. This matter was 

 briefly discussed elsewhere (14). Assuming that the 14 chromosomes 

 are in two similar sets of 7 each, and that homologous members of 

 these sets conjugate except when there is a failure to pair, then when 

 8 chromosomes go to one pole and 6 to the other, both members of one 

 of the pairs must have gone to the same pole. This probably takes 

 place in cases where such members were unconjugated, for the 

 purpose, or at any rate, the result of the pairing is in ordinary cases 

 that one member of every pair shall be distributed to each pole. If, 

 while two members of one pair thus go to one pole, the second member 

 of another pair goes to the other pole, we should have an equal 

 numerical distribution of chromosomes, but one daughter group would 

 be lacking both members of one pair and the other would be lacking 

 both members of another pair. It is highly probable that such a 

 distribution occasionally takes place, though it would be less common 

 than the case, already proved, where the members of a single pair are 

 unilaterally distributed. It should be borne in mind that such cases 

 are most likely to occur, not when the members of a pair are con- 

 jugated, but when they lie separately in diakinesis and on the spindle. 

 Miss Lutz (17), from an examination of root tips, states that she 

 has observed several individuals belonging to different strains having 

 15 chromosomes instead of 14. This is to be anticipated from the 

 irregularities in chromosome distribution in reduction already men- 

 tioned. I have observed one such case in O. lataXO. gigas (14) — 

 a certain plant having 20 chromosomes instead of 21. All the plants 

 of O. lata (12) and O. nanella (13) thus far examined by me had 14 

 chromosomes, while Miss Lutz (17) finds in root tips some O. lata 

 plants with 14 and also some with 15 or she thinks possibly 16 chro- 

 mosomes. She reports finding two O. nanella plants with 14 chro- 

 mosomes and one with 15. Two O. albida seedlings are said to have 

 15 chromosomes and two O. oblonga plants 15, while a third has 14. 

 Disregarding the possibility that these results might be due to the 

 well-known variation in chromosome numbers in root tips, they are 

 such as would be likely to arise in different individuals from the 

 cytological irregularities I have already described. Whether there 



