Lutz, Triploid Mutants in Oenothera. 41 1 



included, and the 20- and 21 -chromosome plants of assumed male 

 parentage have formed the basis of this report upon the offspring 

 of (). lata X 0. gigas. 



The writer in August, 1907 (17) reported that the somatic cells 

 of 0. (jigas had been found to have 28 or 29 chromosomes. In 

 January, 1908 (10) Gates reported 28 for 0. gigas, having determined 

 this number from the study of reduction mitosis in the pollen 

 mother-cells of this form. 0. lata has been repeatedly referred to 

 by Gates as having 14 chromosomes (7, p. 97; 8, p. 11; 10). On 

 the first page of his paper dealing with "The Behavior of Chro- 

 mosomes in 0. lata X ^- yiyus" (13) 0. lata is referred to as 'hav- 

 ing usually 14 chromosomes'. He then says: "if fertilization took 

 place in the ordinary manner, the hybrid 0. lata X 0. gigas would 

 be expected to have 21 chromosomes, 7 derived from the lata egg 

 and 14 (which is probably a double set of Lamarckiana chromosomes) 

 derived from the male cell of 0. gigas". If. therefore, the expecta- 

 tion w r as 21 chromosomes for hybrids of this cross, and the 20- 

 chromosome plant derived from the package of unguarded seeds 

 was included among the offspring of 0. lata X 0. gigas reported 

 in this paper (13) there would appear to have been no reason for 

 excluding the 21 -chromosome plant of unknown male parentage. 

 Furthermore, Gates' statement at the beginning of his paper 

 dealing with "The Behavior of Chromosomes in 0. lata X 0. 

 gigas" appears to confirm the supposition that the hybrids of 

 this report are the 20- and 21 -chromosome plants of unknown male 

 parentage referred to in earlier contributions: 



"The general results regarding chromosome numbers and 

 distribution were obtained some time ago, and a brief statement 

 was published (10), but the cytological evidence is here presented 

 for the first time. Many of the drawings for these figures were 

 completed about two years ago," etc. 



The only offspring of 0. lata X 0. gigas which he mentions 

 in the paper to which he refers the reader ("The Chromosomes of 

 Oenothera") are the two plants of unknown male parentage which 

 he has assumed to be offspring of 0. lata X 0. gigas. While Gates 

 states (13, p. 180) that the 20-chromosome plant included in this 

 report upon "The Behavior of Chromosomes in 0. lata X 0. gigas" 22 ) 

 was derived from a seed-package that had not been guarded, and 



22) Although in his report (13) upon the hybrid offspring of 0. lata X 0. gigas 

 (Jutes quotes (pp. 180 181) from a report upon the Cold Spring Harbor cultures 

 in which a variety of numbers were announced for the somatic cells of the various 

 types of these hybrids, he states in the summary at the conclusion of his paper: 



"0. lata X 0. gigas has 21 chromosomes in its somatic cells, 7 of maternal 

 origin (0. lata) and 14 of paternal origin (0. gigas). In one individual the number 

 was 20, owing probably to the absence of one chromosome'' etc. 



