Lutz, Triploid Mutants in Oenothera. ill! I 



not known whether these two were the 20- and 21-chromosome 

 plants, the 20-chromosome plant and another whose number was 

 twenty or twenty-one' (8, p. 11), or the latter and the 21-chromo- 

 some plant. Since Gates has nowhere stated that these two or 

 three plants were the offspring of separate crosses, it is probable 

 that all were derived from the same lot of seeds, though grown in 

 separate seasons. However, it is perfectly clear from the references 

 which he mentions that the 20-chromosome plant referred to in 

 each of these reports above quoted is the same as that first described 

 as * Lamarcldana hybrid" offspring of 0. lata X 0. Lamarckiana (7). 

 This plant has been so variously classified that the reader is left 

 with no definite knowledge of the real nature of its vegetative 

 characters. It was first described (7, p. 83) as belonging to a group 

 of 10 plants 'which conformed more or less completely to the 

 characters of the pollen parent' ((). Lamarckiana} and was called 

 "0. Lamarckiana hybrid". Next (8, p. 20) it is stated that the pure 

 0. Lamarckiana and the " 0. Lamarckiana hybrid" (which we have 

 seen includes the 20-chromosome plant) 'are identical in external 

 appearance'. In the third paper (10) the 20-chromosome plant was 

 included in a group of offspring of 0. lata X 0. yf'yas described 

 as 'having almost or quite the identical appearance of 0. yiyas'. 

 Lastly (13), it was mentioned in a group of hybrids which 'appeared 

 to have been intermediate between 0. lata and 0. yiyas\ 



In the foot-note (13, p. 180) quoted above in which Gates 

 described the origin of the 20-chromosome plant, the last statement 

 is not entirely clear. It is probable that he intended to state that 

 the fertilization of the plant from which the package of seed was 

 obtained, was unguarded. This is indicated by the use of the term 

 "foreign gigns pollen". To accept his meaning as stated would 

 throw both parents in question. If, however, it was his intention 

 to convey the thought suggested, then the question arises as to 

 how one can know that the unguarded fertilization of any form 

 was effected by 0. yiyas pollen. Even though there were no prim- 

 roses growing in the garden except (). lata and 0. yiyas at the time 

 fertilization occurred, it could be assumed only as a probability, 

 for 0. lata, whose anthers are usually dry and barren, occa- 

 sionally produces a tiny bit of pollen which is capable of fertiliza- 

 tion. In evidence of this fact, I have grown six cultures of 0. lata 

 at Cold Spring Harbor from six separate individuals of 0. Inln 

 self-pollinated. This was accomplished only by gathering all of 

 the unsplit buds from a number of individuals in the morning of 

 the flowering day for days or weeks as necessary. These were 

 then carefully opened in the laboratory, and when, rarely, a tiny 

 bit of pollen was found, it was used to self-pollinate a guarded 

 flower of the plant from which it was derived. 



