|4() Gates, Tetraploid Mutants and Chromosome Mechanisms. 



myself, together with those of Geerts and Davis, on the pheno- 

 mena of meiosis in these forms. These interesting suggestions need 

 not concern us now, but they by no means exhaust the possibilities, 

 and at least one other cause of chromosome diminution is as likely 

 to occur as some that she mentions, namely, the loss of extra chro- 

 mosomes from the nuclei during the early divisions of the embryo. 

 1 presented certain evidence for this earlier in the present paper. 

 The nuclear divisions of the male gametophyte are also a likely 

 place for loss of chromosomes to take place from an unbalanced 

 chromosome group. It is also conceivable that the two male nuclei 

 in a pollen tube might in this way come to have different chromo- 

 some numbers. 



In connection with her discussion of the chromosome numbers 

 in Oenothera, Miss Lutz (p. 432) makes the extraordinary statement, 

 "So far as I have been able to discover, no mention has been 

 made of differences of chromosome number in mutants of Oeno- 

 thera previous to Gates' first paper. In this contribution he men- 

 tions no mutant with a chromosome number differing from that of 

 0. Lamarcldana" And in the following paragraph, "The first men- 

 tion of a mutant with a chromosome number differing from that 

 of 0. Lamarckiana was published by the writer six months later". 

 From this the reader is left to infer that she (Miss Lutz) made 

 the first discovery of different chromosome numbers in Oenothera. 

 But it is probably well-known to every one, except perhaps Miss 

 Lutz, that the whole subject of chromosome numbers in Oenothera 

 was opened up by my paper (1907), in which it was clearly shown 

 that one plant had about fourteen chromosomes and another about 

 twenty. The first announcement of these results was made in my 

 paper read at the New York meeting of the American Association 

 for Advancement of Science, in December, 1906. And it is not 

 devoid of significance that Miss Lutz began her work with Oeno- 

 fltrra seedling root-tips in January, 1907 (as she herself admits, 

 1912, footnote, p. 389), i. e., within a few days of the original 

 announcement of my discovery. 



Remarks on giantism in Oenothera. 



In the previous sections of this paper I have dealt with various 

 yiyas types now known in Ociwthera, together with some of their 

 derivatives and hybrids. The variability of certain of these yiyas 

 races has been described recently by Nilsson (1912), and by me 

 in a paper now in press. It is becoming obvious from facts regard- 

 ing the pollen grains, already mentioned in this paper, and also 

 from the chromosome numbers in the various yiyas forms so far 

 as they have been determined, that the varying chromosome distribu- 

 tions in the giant forms are the real cause of many at least of 



