Lutz, Triploid Mutants in Oenotlicix. \',\\ 



only seven La march iana chromosomes would produce a Lamarck- 

 iiina plant, a situation which is highly improbable, to say the least. 



"(3) Another possibility is that all the eggs of 0. lata have the 

 unreduced number of chromosomes, and that part of them develop 

 without fertilization (parthenogenetically), producing O. lata plants 

 with 14 chromosomes; while others are fertilized with 0. Lamar- 

 ckiaHti pollen and produce Lamnrckiana plants having twenty-one 

 chromosomes (fig. 3). This assumption in perhaps as reasonable as 

 any, but no case is known of an unreduced egg being fertilized." 



We now know that O. lata has 15 chromosomes and O. Lamar- 

 rkiana 14. It is furthermore impossible to concede that all the 

 eggs of O. lata may have the unreduced number of chromosomes, 

 as Gates has here suggested. If such were the case, and 0. lata 

 had 14 chromosomes as he has stated, the fertilization of 0. lata 

 by 0. lata should give only 21 -chromosome offspring, provided the 

 maturation process in the male and female germ cells had been 

 regular. If 0. lata has 15 chromosomes as I have found, then the 

 fertilization of unreduced female germ cells with normally reduced 

 male, should give 22- and 23-chromosome offspring only. 



I have determined the somatic chromosome number of but 

 33 offspring of 0. lata self-pollinated thus far (exclusive of a few 

 plants of Dr. D. T. MacDougal's culture, not derived from seeds 

 or plants from de Vries), and but one of this number was found 

 to have 21 chromosomes and one other 22. No one of the remaining 

 31 had a chromosome number anywhere in the region of 21, 22 

 or 23. 



Later (13), in referring to the somatic chromosome numbers 

 reported for the Cold Spring Harbor culture of 0. lata X 0. yiyas, 

 Gates states that the two lata-like hybrids of this cross having 

 each 15 chromosomes may have been apogamously derived. In a 

 short paper published a few months later (14) he again refers to 

 the subject and makes the following statement: 



"Whether these hybrids all had the same individual 0. lata 

 plant as mother is not stated, but if this was the case and the 

 mother had fifteen chromosomes, then we might expect the two 

 lata plants in the offspring both to have fifteen chromosomes, and 

 the hybrids of class III to have twenty-one or twenty-two chromo- 

 somes (14-t~ 7 or 14 -|- 8), while in the case of the 0. (jiyas-like 

 plants which are stated to have had thirty chromosomes in the 

 individuals in which a count was made, the expectation would 

 perhaps be twenty-nine (15 -f- 14). 



"How the 0. nigas-like individuals having about thirty chro- 

 mosomes originated must, however, be a matter of conjecture at 

 the present time." 



