Lutz, Triploid Mutants in Oenothera. 



instances. However, he mentions a very interesting irregularity in 

 the heterotypic mitosis of 0. gigas of the same nature as the second 

 type referred to by Gates. He says (4, p. 957): 



"In this case two pairs of chromosomes had lagged behind 

 the main group in passing to the poles of the spindle, and were 

 associated in a small secondary spindle within the main structure. That 

 %uch stray chromosomes, as well as the main group with a chro- 

 mosome content smaller than the normal, may form independent 

 nuclei is illustrated in Fig. 70. It is, however, improbable that 

 fertile pollen-grains can be developed under such abnormal condi- 

 tions. The fact that the chromosomes in these nuclei have lost 

 their usual form and by anastomosing appear to be developing a 

 chromatic reticulum, indicates that the nuclei do not proceed 

 further towards the homotypic mitosis, but probably pass into a 

 resting condition." 



If the 75 offspring of the Cold Spring Harbor 21 -chromosome mu- 

 tant (5483) persisted in their Lamarckiana characters throughout their 

 life histories (and it is practically certain that the majority did if they 

 bore no other than Lamarckiana characters throughout the greenhouse 

 rosette stage 16 )), it would indicate that these offspring wciv ' ll 



of such irregularities in the heterotypic divisions of the germ <- 's 

 of the parent as were described by Geerts for the g ;rm cells >t' 

 21-chromosome hybrids. Furthermore, the presence of 75 such 

 offspring in a total of 98 described would indicate that this phen- 

 omenon is of very common occurrence. 



However, from the fact that a few of the offspring of these 

 mutants were described as having vegetative characters resembling 

 those of 0. gigas more or less in the early rosette stage, I believe 

 that we shall find, with more extended studies, that occasionally 

 numbers of normal chromosomes in excess of 14 (perhaps ranging 

 all the way from 14 to 21) are distributed to the poles of the spindle 

 at the reduction division of 21-chromosome plants 17 ). The two poles 

 in such cases might receive equal or unequal numbers of chromo- 

 somes. It is obvious that one must necessarily receive one more 

 than the other when the total number reaching the poles is 15, 17, 

 19, or 21. From this irregular distribution, I believe that germ cells 

 sometimes result with a number of normal chromosomes in excess 

 of 7. Let us assume that all of the 21 chromosomes occasionally reach 



10) A recent communication from Dr. Shull states that 73 of the 75 offspring 

 displayed no other than Lamarckiana characters throughout the season. Of the 

 remaining two, one, at least, showed certain points of resemblance to 0. gigas. 



17) The second paragraph quoted from Geerts on p. 399 of this report clearly 

 shows that a number of chromosomes (or remnants of chromosomes) in excess of 

 14 are sometimes distributed to the poles of the spindle at the reduction division 

 s" from 0. lata X U- 



