560 



DOUBLED CHROMOSOMES OF OENOTHERA 



strength, and compare them with the numbers of chromosomes, 

 we get the data given in table I. 



In order to get an easier survey we combine the figures into 

 groups, and calculate their percentages (table II). This table shows 

 that the larger part of the normal plants had 14—15 chromosomes, 

 whereas the rosettes had mostly an abnormally high number. In 

 other words, the development is the more incomplete, the larger the 

 number of mutated chromosomes. From this we may safely con- 

 clude that among the sterile seeds the high chromosome numbers 



Table I 



Fall of 1923 



must prevail, leaving only a small proportion for the viable germs, 

 and this is sufficient proof for the validity of the assumption just 

 made. 



Chromosomes and external features 



In studying the progeny of another form of semigigas, one of the 

 writers found that the offspring may be combined into groups, and 

 that the majority of these correspond to the dimorphic mutants 



