104 SIRKS, THE COLOURFACTORS OF THE SEEDCOAT IN PHASEOLUS 
hybrid A A B b segregate into three groups: 1 À AB B:2 A À 
B b : 1 À À b b or 1 selfcoloured : 2 marbled : 1 white. Segre- 
gations from an A A B b C c-hybrid, in which C in collaboration 
with A causes a colouring of the whole seedcoat, the navelring 
inclusive, go according to IAABBCC: 2AABBCe : 
LAABBcc:2AABbCC:4 A A Bb Cc: 2 AAB 
bec: 1.A:AbbCC:2:A.A bb Cæ:1 AvA: bob cc; these 
16 combinations may be grouped into 8 marbled (all with B b), 
7 selfcoloured and 1 (A A b bcc) white; thus a proportion of 
8 marbled: 7 selfcoloured or 53.30/, of marbled individuals. These 
results have led Kooıman to his opinion that the factor for con- 
stant marbling (called by him M) would be of a character essen- 
tially different from his B-factor. This M-factor is dominant over 
the recessive uniformity in colour, and shows an Fo-segregation 
along 3 : 1. | 
Besides marbling as seedcoatpattern, anôther design is shown 
by some races: a striping, by which the colours are restrained to 
long, almost ellipsoidical stripes with the navel in one of the long 
sides of these ellipses. This character also may be ascribed to 
one dominant factor, by most authors indicated as S with mono- 
hybridical segregation. TSCHERMAK believes this factor S to be 
hypostatic to the marbling factor M. 
As last factor for special designs the factor or factors for eyedness 
‚may be mentioned. This peculiar colourpattern was studied by 
EMERSON; from his observations on its segregation he concluded 
to the existence of a pair of factors T-t; T causes the extension 
of the colour upon the whole seedcoat (totality); in t- individuals 
this colour is restrained to a relatively small part around the 
navel, as an eye of pigmentation. Totality of colour was dominant 
in F,; the Fo segregated into 3 total-coloured: 1 eyed individuals. 
Concerning this T-factor EMERSON suggested the possibility of its 
presence in white beans in a state of latency. Thus four genotypes 
may be found: PT = totally coloured; Pt = eyed, pT and pt 
whites, one with the other without the latent factor for total 
colouring. 
Of course it will be possible, as EMERSON already has remarked, 
that more genetic factors are at work in the process of colourex- 
tension: for example besides P-p and T-t still another pair E-e, that 



