100 sIRKS, THE COLOURFACTORS OF THE SEEDCOAT IN PHASEOLUS 
plants; in c-w-splitting F3-families 596c : 177w and in c-w-split- 
ting Fy-cultures 226 coloured: 78 white plants, or totals of 1310 
coloured: 416 whites, or 3.15:1. In 1912 TSCHERMAK has indicated 
this chromogenic groundfactor, the absence of which makes the | 
seedcoat white, while presence or absence of other colourfactors 
is of no importance, as A. And EMERSON has published like 
results in his papers (1902, 1904, 1909 a and b), that form excel- 
lent complements to TSCHERMAKS researches. Crosses between 
coloured and white-seeded plants in Phaseolus vulgaris gave in 
his cultures in F, always coloured seedcoats, in F2 280 with and 
111 without pigmentation, and in splitting Fs-families 191 coloured 
70 white plants. Nearly a 3:1- proportion, that led EMERSON to 
the conclusion of the presence of a factor P for pigmentation: 
p or the absence of P giving white seedcoats. This factor has 
since been found by SHULL, SHAW and NORTON and myself and 
indicated as P; TJEBBES and KooïMAN (1919) named it F and 
KooïMAN (1920) again A. With regard to its absence all authors 
are unanimous; while it remains uncertain, if its presence without 
the other colourfactors, involves any observable result. TSCHERMAK 
(1912) ascribes to the unaccompanied presence of his chromogenic 
éroundfactor a yellowbrown colour (as shown by his yellowish 
brown race „Non plus ultra” with formula Abcm), while EMERSON 
(1909, p. 100) is of another opposite opinion: crossing of two 
coloured beans, that have no common colourfactors, may led to 
the birth of a certain percentage of white-seeded F,-plants, as in 
these cases the white colour is caused by the absence of all pig- 
ment-building factors and presence of the P-factor only. Cros- 
sing a white bean, produced in this way with another white 
one, that lacks the factor for pigmentation, but possesses other 
colourfactors, will give therefore a coloured Fy-generation. And 
SHAW and Norton (1918, p. 65) have obtained indeed a coloured 
posterity by crossing two whites (Davis Wax X Michigan 
White Wax). It may be regretted, that they have, as far as I know, 
not yet published more detailed results about the posterities, 
grown from this important hybrid. The existence of two types of 
white-seeded plants implies that not all Fo-generations from a 
coloured-white crossing will segregate according to 3:1; if the 
white parent (p) has not all other factors in common with the 








