342 CARL HALLQVIST 
analysis of this cross shall establish a crossover percentage higher 
than 2 %. It will probably be found that the percentage does not exceed 
1 %; it will rather fall below this figure, as the chances of a cross- 
over percentage more or less than */, % are equal, as shown on 
pag. 316. The factors B and F are then situated in the closest proxi- 
mity to each other. According to cross 9 there is linkage between 
B and V to a degree corresponding to a crossover percentage of 
about 22 %. The F;-analysis gives the value 20,4, and the F,-analysis 
23,83. The same crossover percentage is to be expected between the 
factors V and F on account of the closeness between the factors B 
and F. The values obtained in the case of V—F are 27 % according 
to the F,-analysis, but 222 % according to the F;-analysis. The F;- 
result shows thus a striking correspondence with the expectation. 
The location of the factors B, V and F in the chromosome may 
then be demonstrated in the following way. 
ze 
BF V 

It should be stated that the mutual location of the proximate 
factors B and F is rather gratuitous. All crosses have shown that the 
fourth flower colour factor, the pure red factor R, operates independent 
of the other factors; it is probably situated in another chromosome. 
The same is probably true of the marbling factor, which has been 
shown to be independent of the B-factor. The relation of the M-factor 
to the fundamental factor R is not yet known. 
The coupling between the factors B and V is particularly inte- 
resting. The linkage between these factors is very close; it is perhaps 
complete, as no crossovers have been found. This might favour the 
supposition that the present case should be interpreted as a case of 
multiple allelomorphs. This is erroneous, however, as seen below. The 
factor denotation used by MorGax has been adopted in the following 
presentation of the facts. In order to avoid confusion with the pre- 
sence-absence system previously employed, only large letters have been 
used; commas and "symbols have been used as indices of mutations (see 
MorGan 1915 pag. 219). 
BV = blue, wildtype; BV’=violet; B’V = bluish red; B’V’ = 
pure red; BV~= tinged blue; B’/V~= tinged red. 
It should be observed that violet colour, for instance, is here cal- 
led V~contrary to the presence-absence indices, where violet is denoted, 
V, while v denotes bluish red. 
