562 



DOUBLED CHROMOSOMES OF OENOTHERA 



tion of lata and cana, were represented in high and almost equal 

 numbers (10—13.5 per cent), whereas the secondary types were 

 present in only one or two specimens each. There are seven main 

 groups, including lata but omitting Lamar cki ana, and this points 

 to the conception that each of them corresponds to one of the seven 

 chromosomes of the haploid nucleus. 



If we apply the law of probability not only to the numbers of 

 the chromosomes, but also to their qualities, we may consider it 

 very probable that the different chromosomes will be equally repre- 

 sented among the different groups of seedlings. Thus we should 



Table III 



Groups according to prototypes 



Prototypes 



lata 



scintillans 



oblonga 



auricula 



cana 



candicans 



pallescens 



liquida 



spathulata 



hamata 



pulla 



Lamarckiana 



Total 



Num- 

 ber 



2 



10 

 1 

 2 



18 

 1 

 8 

 9 



11 

 2 



10 

 6 



80 



Percen- 

 tage 



2.5 

 12.5 



1.3 



2.5 

 22.5 



1.3 

 10.0 

 11.3 

 13.5 



2.5 

 12.5 



7.5 



expect seven main groups of mutant characters to be represented 

 with about equal frequency, each corresponding to the doubling 

 of a distinct nuclear rod. The expected groups would then corres- 

 pond to the observed ones. Why the type of lata should be rarer 

 and that of cana more frequent remains obscure. In this respect, 

 however, it should be remembered that among the progeny of 0. 

 perennis (0. (blandinax simplex) semigigas), another group, that of 

 the type of scintillans, is in the majority, a fact which obviously 

 diminishes the importance of such deviations. From this we may 

 infer that the different chromosomes are the bearers of distinct 

 groups of mutant characters, or, in other words, that each chromo- 

 some is the bearer of the factors of one of the seven main types of 

 table III. This conclusion is in harmony with the hypothesis of 

 the distribution of mutant characters among the chromosomes, and 



