FLOWER AND SEED COLOUR IN LUPINUS 343 


According to the above symbols the non-appearance of the tinged ~ 
violet type in F, of cros$ 8 (tinged blue X violet) should depend on 
the fact that the factor producing the dilution of the blue colour and 
the factor responsible for the violet colour, denoted V7 and V’ respec- 
tively, are different allelomorphs of the same wildtype factor V. 
Already the F,-result of this cross invalidates this assumption. If 
correct, no synthesis of the wildtype would be obtained from the cross 
BV’ X BV’; this synthesis was secured, however. 
Another supposition is: that the wildtype factor B, which produces 
bluish red flower colour when mutating into B’, also should give rise to 
B- and B’- mutations causing the formation of tinged blue (BV) and 
tinged red (BV), is likewise out of question. The non-appearance of 
tinged violet should then depend on the fact that the V-factor did not 
mutate in an analogous way. The synthesis of blue in the cross bluish 
red X tinged blue (B’V X BV) would not be obtained in the case of 
such a factor construction. | | 
The present case of coupling can not be interpreted as a case of 
multiple allelomorphs, as seen; it is linkage, and it is perhaps complete. 
It is very difficult to determine, however, whether the linkage 
is partial or complete. The non-appearance of the crossovers may 
be explained by assuming a corresponding displacement of the linkage 
value, and the comprehensiveness of the analysis cannot alone decide 
the matter. Indeed, it is doubtful whether there is such a condition 
as complete linkage. The term becomes superfluous if only the clo- 
sest partial linkage conceivable is considered. The question becomes 
another if the assumption is made that two factors are able to lie 
side by side in the same chromomere without excluding each other 
as multiple allelomorphs. The term complete linkage would then 
imply a definite meaning distinguished from partial linkage, and 
essentially different from multiple allelomorphism. There is nothing 
in point of principle to say against such an assumption, as the idea of 
the chomomeres only expresses the belief of the breaking up of the 
chromosomes into their constituent elements. The chromomeres re- 
present the smallest parts of division of the chromosomes, which does 
not imply, however, that they each carry only one factor. 
Some of the essential facts of the inheritance of the flower colour 
and of the seed colour in Lupinus angustifolius have now been presen- 
ted. The definite fixing of the linkage values, the precise relation of 
the marbling factor to the other factors, and the complete analysis 
