4()N Lutz, Triploid Mutants in Oenothera. 



but which appeared to have all the characters of 0. yiyas and was 

 found to have 21 chromosomes. This, with other evidence, furnishes 

 definite proof that the cross which was believed to be pure had 

 been partly pollinated with 0. yiyas"}. 



And in conclusion: 



"0. gigas has 28 chromosomes, and certain plants appearing 

 in the first hybrid generation of 0. lata X 0. yiyas having almost 

 or quite the identical appearance of 0. gigas have 21 chromosomes 

 (20 in one plant)," the latter segregating equally in reduction," etc. 



In still another paper entitled ,,The Behavior of Chromosomes 

 in 0. lata X 0. gigas" published in September, 1909, he states as 

 a preliminary to the cytological discussions which follow: 



"The plants from which these studies were made were grown 

 at Wood's Hole, Mass., in 1905 and 1906, from seeds of De Vries. 

 The results show that in some cases the number of chromosomes 

 is undoubtedly 21, while in one individual it was 20 2 . The number 

 is undoubtedly constant in an individual, however, as shown by a 

 large number of counts, which demonstrated constantly 20 in one 

 case and 21 in the other". 



"The external characters were not studied with sufficient care 

 at that time to describe them accurately, but from my notes they 

 appear to have been intermediate between O. kita and 0. gigas." 



And in the note referred to: 



" 2 In my first paper (8) this individual was thought to be 

 0. lata X 0. Lamarckiana, but was afterwards found to be derived 

 from fertilization by foreign gig as pollen, this particular seed package 

 not having been guarded as was supposed when the seeds were 

 planted" 21 ). 



The evidence is not clear concerning the number of " La mar- 

 ch- i ana hybrids" studied, for there is nothing to indicate whether 

 the 21-chromosome plant referred to in "The Chromosomes of 

 Oenothera" was one of the two mentioned in the previous report 

 (8, p. 10) or whether it was a third individual. Since he states, as 

 quoted above, that the two were grown in different seasons, it is 



20) This statement, together with the use of the term "foreign gigas pollen" 

 in referring (13, p. 180) to the origin of the 20-chromosome plant of this culture, 

 precludes the possibility of these plants having arisen from a sowing of mixed seed, 

 a portion of which had been derived from the guarded fertilization of 0. lata X 0. 

 Lamarckiana and the remainder from the guarded fertilization of 0. lata by 

 0. gigas. 



21) This plant was mentioned as an offspring of 0. lata X 0. gigas in two 

 papers published by Gates (11, p. 28; 12, p. 540), without any statement concerning 

 its uncertain origin in cither case other than that which is contained in the paper 

 to which the reader is referred in the second publication. Such statements are 

 certainly very misleading. 



