376 



STUDIES IN SEEDS AND FRUITS 



The con- 

 ditions in 

 which the 

 mottling of 

 Vicia seeds 

 takes place 



possible that the association is in a sense accidental, and that, 

 as in the berry and capsule, seed-coloration may occur in the 

 green moist legume. 



The seeds of Vicia sepium and Vicia sativa, which are 

 usually mottled with black spots on a dark green or greyish- 

 green ground, will first serve to illustrate this point. After 

 examining a considerable number of their seeds, one might 

 think that these plants produced in each case three kinds of 

 seeds as far as coloration is concerned. There are first the 

 greyish or greenish-grey seeds, then the seeds with the same 

 green or grey ground-colours, but mottled with black spots, 

 and then the seeds that are almost uniformly black, the 

 mottled seeds being the most frequent and the most typical. 

 A closer inspection soon makes it clear that the seemingly 

 uniform black colour really arises from an intensification of the 

 mottling, and that, in fact, all three kinds have the same ground- 

 colour, the differences being due to the variation in the extent 

 of the mottling. In one seed it is almost absent ; in the 

 typical seed it is well developed ; and in another it is so dense 

 that the mottled patches largely coalesce. 



In both these species of Vicia the soft seed of the green 

 pod is green, with an embryo of a darker green. When the 

 blackening and drying of the pod is well advanced these seeds 

 gradually shrink, harden, and become duller or paler in hue, 

 and then the black mottling appears, the shrinking of the 

 cord ushering in the earlier changes. Long before the dehis- 

 cence of the pod the typical characters of the resting seed have 

 been formed, and the embryo exchanges the dark green hue 

 of the unripe soft seed for the dull yellowish colour that is so 

 characteristic of the resting state of seeds. 



With regard to the conditions under which the dark 

 coloration of the seeds of these two species of Vicia occurs, 

 the following remarks may be made. On the plant the drying 

 and blackening of the pod precede the mottling of the seeds, 

 which belongs to the latter stage of the shrinking and harden- 

 ing process. But it appears to be essential for the develop- 



