SEED-COLORATION 375 



to the air. Though checked by plants in pots kept indoors, 

 the results as described below were all obtained from plants 

 growing in a hedgerow and exposed to the ordinary weather- 

 conditions. In the early stage, when the young seeds are 

 little more than bags of fluid, they are pearly white. As the 

 seeds mature and their contents solidify, they become succes- 

 sively dull white, yellowish, reddish brown, and finally shining 

 black. The colouring stages and the maturation are completed 

 in the green moist capsule before dehiscence. When the 

 fruits were incised in the middle of June the seeds exposed 

 were soft pearl-like bodies, which, if detached and allowed to 

 dry, shrank to a mere skin. By the beginning of August the 

 exposed seeds had reached the brown stage, the last but one 

 of the stages of the colouring process ; but with the exception 

 of the difference in hue and their rather smaller size they were 

 normal hard matured seeds. In the other two closed cells of 

 each capsule experimented on, the seeds during this period 

 acquired the typical black colour and were normal in their 

 other characters. The experiment did not seem to affect the 

 rate of the changes in the seeds of the other two uncut cells ; 

 and when the capsules of other plants around were dehiscing, 

 these two cells were doing the same, displaying normal black 

 seeds that contrasted in their hue with the brown seeds exposed 

 in the incised cell. The upshot of these experiments is that 

 the exposed seeds developed normally, with the exception of 

 their failure to acquire the final black colour, for which en- 

 closure in the fruit seems requisite. 



The foregoing experiment on the seeds of S cilia nutans will The blacken- 

 serve to illustrate the complexity of the processes involved 

 in seed-coloration. 1 will now proceed to discuss more at 

 length the conditions under which seeds colour in leguminous 

 pods, and in the first place I will take the blackening and black 

 mottling of seeds. One of the chief points which we will 

 endeavour to determine will be the connection between the 

 coloration of the seed and the drying of the pod. Though 

 the two processes are so frequently associated, it is quite 



