SEED-COLORATION 389 



Nor can we look for an explanation of this variation in The colour 

 colour of the resting seed to the colour of the embryo in the bryoln the 

 pre-resting or unripe seed. Thus exalbuminous seeds like ^n^'reYS 

 those of Pisum sativum (unwrinkled variety), C^salpinia Sappan. seeds has no 

 -rr- • • ^ • 7-7 1 • 1 1- 1 influence on 



Ulex europ^us^ Vicia sattva^ Lytisus Laburnum^ etc., which display the final 



great differences in coloration in the resting seed, all have ie°^minous^ 



green embryos as well as green coverings in the soft unripe s^®*^- 



condition ; and the same remark applies to the albuminous 



seeds of Bauhinia^ Cassia fistula^ and Poinciana regia. 



If we expect to find a clue in the colour of the leguminous 



embryo in the resting state, we shall be also disappointed. 



There is a uniformity of colouring in the embryo of the 



resting exalbuminous seed which stands in no sort of relation 



with the varied colouring of the coats of such seeds. As the 



green embryo enters the resting state, its assumption of a pale 



yellow or brownish-yellow hue indicates the destruction of the 



chlorophyll. That green embryos thus change their colour 



when the immature soft seed contracts and hardens in the 



shrinking stage seems to be a general rule. This is brought 



out by the table below in my discussion of green embryos of 



leguminous seeds ; but more examples might be given, where, 



although I have no note of the colour of the embryo in the 



immature seed, its green colour is indicated by its yellowish 



coloration in the resting seed, as, for instance, in Albizzia 



Lebbek. 



In making further reference to the green embryos so In unripe 

 ^ r , ■ . -1 • J leguminous 



commonly round in unripe or pre-resting leguminous seeds, seeds green 



one must notice that when the embryo is green the seed-coat is g'^g'^'^^coats*^ 

 generally green, but of a markedly paler shade. However, it "^"^J'j ^° 

 is not difficult to find exceptions to the rule amongst exal- 

 buminous seeds. Thus with Entada polystachya the coats of 

 the soft unripe seed are white, but the enclosed embryo is 

 bright green ; whilst with the Broad Bean {Faba vulgaris^ the 

 embryo is bright green and the coats are white, tinged faintly 

 with greenish yellow. Nevertheless, as indicated in the 

 samples given in the table below, it is evidently the rule for 



