566 DOUBLED CHROMOSOMES OF OENOTHERA 



Prototype scintillans. — In 1923 we had a large bed of scintillans 

 xblandina in order to compare the mutants with this hybrid. The 

 cross had been made in 1919, and the culture of 1923 was the second 

 generation, which embraced about 20 specimens of the type of 

 scintillans, with the same dark green and shining leaves, but con- 

 siderably narrower than those of the race. This was especially evident 

 during the period of the rosettes, and at this time four of the mutants 

 were exactly like the hybrid prototype, which carried the characters 

 of 0. Lamarckiana mut. velutina (0. blandina) in the paternal halves 

 of their nuclei. Of these four mutants, two had 15 chromosomes 

 and the two others 17. The two first remained true to their hybrid 

 pattern during their whole life, but of the two latter one distinguished 

 itself at the flowering period by a broader foliage. The fourth one 

 stayed in the condition of a rosette until the fall. 



Among the remaining six specimens, three were narrow leaved 

 and three broad leaved in comparison with the typical ones. The 

 first had 16, 18, and 19 chromosomes, and the latter 16, 16, and 

 18. Sundry smaller differences were observed among them, as was 

 to be expected, but the main type was in every case that of the 

 group. One narrow leaved and one broad leaved plant have not 

 succeeded in developing a stem in the first year (chromosomes 

 18. and 19). 



One specimen of oblonga occurred. It was easily recognized when 

 still very young, and remained throughout life true to its type. Of 

 auricula, two specimens were observed (with 15 and 17 chromo- 

 somes). We had a culture of 16 flowering plants of the fourth gene- 

 ration of the race of that name for comparison. The rosettes are 

 easily confused with those of cana, but the stout stems, large flower- 

 buds, and broad fruits cannot leave any doubt. Differences between 

 the two mutants and the race have not been observed. 



Prototype pallescens. — Only one plant of this group had 15 

 chromosomes. It was almost like the normal race, but had somewhat 

 broader leaves, especially in its youth. Three specimens had 16 

 chromosomes, one of them remained a rosette, whereas the two 

 others flowered but produced hardly any pollen. The same condition 

 prevailed for a plant with 17 and another with 19 chromosomes, 

 and another plant with the latter number did not flower. Among 

 the flowering plants of this group a curious deviation occurred more 

 or less often, consisting in swollen stigma lobes which broadened the 

 tops of the flower buds before opening. One plant with 20 chromo- 

 somes was free from this disease, and produced enough pollen for 



