340 CARL HALLQVIST 


tical affinity but not yet proved to be related physiologically or 
chemically. It is, naturally, of great importance to know if the 
morphological effect of the one and same factor is due to circum- 
stances conditioned by different developmental stages of the plant, dif- 
ferent conditions prevailing in the different organs of the plant, or, 
on the contrary, if the factor itself is differentiated in some way. Thus 
the study of pleiotropic phenomena becomes of great weight when 
the nature of the genetical factors is brought under consideration. 
THE SEED COLOUR. 
The observations made with regard to the seed colour have been 
stated in the above in connection with the flower colours; they have 
been assumed to arise from the same factors due to the pleiotropic 
nature of these factors. The results of the segregations agree also 
throughout with this interpretation; they allow also the assumption, 
however, that specific seed colour factors are closely coupled with 
the flower colour factors. This is, however, very uncertain, even 
if certain facts would seem to point in this direction, as for instance 
the fact the V-factor, as well as the full colour factor, do not influence 
the seed colour. The evidence obtained, however, does not support 
the giving up of the assumption made, that the flower colour factors 
also determine the colour of the seeds. 
There is one character of the seed colour, however, that has 
not yet been treated, viz. the marbling. Two types differing in the 
distribution of the pigment have been described on pag. 303. The 
earth-brown and the rust-brown colour are either marbled or evenly 
distributed to full intensity over the whole surface of the seed, with 
the exception for small distinct white flecks. The marbling is 
brought about by the scattered distribution of the pigment grains in 
flecks of irregular form and extent. The colour of these flecks is 
gray, and small white flecks also occur here. Marbling dominates 
over non-marbling, and F, segregates in the ratio 3:1. In cross 2, 
the only cross where the non-marbled variety has been used, the 
following results have been obtained: 
215 marbled : 63 non-marbled 
expected : 208,5 69,5 D/M = =0,». 
The weakening of the colour, which is characteristic of the gray 
flecks, does not involve an intensifying of the colour in the marbled 
