APPENDIX 



491 



the previous loss of weight of the . seed-coverings is not taken into 

 account, the second for the same seed where this loss is allowed for. 



. The Shrinking and Swelling Regimes of the Seeds of 

 hura crepitans. 



Here we see that when determining the shrinkage for the mature 

 resting seed we are ascertaining its full amount for the kernel but not 

 for the coverings, which, instead of losing 75 per cent, of their weight 

 in the shrinking process, really lose as much as 82 per cent, during the 

 whole stage. 



That the albumen and embryo which constitute the kernel increase 

 in weight, and by implication in size, after the seed-coverings have 

 begun to contract and dry, is clearly indicated in the table below. The 

 growth in size of the embryo is not there shown, but it may be observed 

 that when the coats have attained their maximum size and weight, the 

 embryo, though completely formed, is only about one-fourth of the 

 mature size and covers only a third of the surface of the albumen. 

 That the growth of the albumen and the embryo is much behind the 

 growth of the seed-coats becomes very evident when one handles the 

 seeds, the embryo in its turn being less advanced than the albumen. 



It is also brought out in the table that the shrinkage of the coats 

 during the maturation of the kernel is confined to the inner layer, 

 which is semi-crustaceous in the early stage and contracts and hardens 

 as the kernel matures. 



Another peculiarity in the seeds of Hura crepitans, which it shares 

 with other seeds possessing oily kernels, is the small amount of water 

 taken up when swelling for germination (see pp. 208, 214). Whilst 

 in leguminous seeds displaying the same structure, as in Poinciana, 

 Cassia, and Bauhinia, the swelling kernel on the average increases its 

 weight by about 150 per cent., in Hura the kernel adds barely 70 



