SEED-COLORATION 379 



ground. This blackening process accompanies the early- 

 shrinking and hardening of the soft, white pre-resting seed, 

 and is most active after the seed has lost 20 per cent, of its 

 weight ; but although often associated with the drying of the 

 pod, there is good reason for holding that these changes in the 

 colour, size, and consistence of the seed may occur, as in the 

 berry, under very moist conditions. 



Whilst observing the habits of the plants of Dioclea reflexa The con- 

 in their home in the forests of the Grand Etang in Grenada, I seed-color 



was 



able to notice the conditions under which the seed-colora- ascTrtSned 



tion took place. Whilst the reddish-brown and the mottled Jj ob^J2;_ 

 seeds represented those that had undergone the greatest periment. 

 amount of drying in the pod on the plant, the black seeds 

 were invariably those obtained from pods lying on the ground 

 in the most humid parts of the forest, where the seeds failed 

 to dry properly, and, as remarked in another page, sometimes 

 dispensed with the resting stage and germinated in the pod. 

 Such black seeds, when not germinating, possessed coats 

 insufficiently hardened and still somewhat flexible. 



Another indication that the blackening of the seeds of 

 Bioclea reflexa is most complete under moist conditions was 

 afforded by the circumstance that when the soft, white unripe 

 seeds were detached and allowed to dry in a room they always 

 began to colour and to mottle on the under surface, and were 

 always much darker below than above. After three or four 

 days the under surface was usually uniformly black, whilst the 

 upper surface was only mottled. Such seeds when examined 

 proved to be sensibly softer and considerably moister on the 

 lower than on the upper side. Hence it was evident that 

 a moist surface favoured the blackening process, whilst a 

 rapidly drying surface retarded it. 



Very instructive is the behaviour of the mottled seeds of J^hemottling 

 Phaseolus multiflorus (Scarlet-runner). That the source of the ofPhaseolus 

 colouring is in the coats alone and is not connected with the J^"arlet-"^ 

 coloration of the embryo is apparently indicated in the fact runner), 

 that the embryo is pale green in the unripe or pre-restmg 



