2l6 



STUDIES IN SEEDS AND FRUITS 



The role of 

 the embr^^o 

 in the shrink- 

 ing- and 

 ^swelling 

 ^stages of 

 albuminous 

 seeds. 



In young seeds weighing about 8 grains (when the coats make 

 up one-fourth of the seed's diameter) the weight of the 

 coverings is about 37 per cent, of that of the entire seed. 

 In the mature soft seeds, weighing 12 grains, the proportional 

 weight of the coats is reduced to 27 per cent. In all cases, one 

 may add, there is a further decrease in the relative weight of 

 the coverings in the resting seed. Taking the approximate 

 data for the different stages, we obtain the following results : — 



The Relative Weight of the Coats of the Pre-resting Seed in 



DIFFERENT STAGES AND OF THE RESTING SeED, STATED AS" A 



Percentage of the Weight of the Entire Seed. 



Not the least interesting feature of this discussion relating 

 to the proportion of parts in the three conditions of the seed 

 is that concerning the r61e taken by the embryo in albuminous 

 seeds. I deal here only with types of those dicotyledonous 

 seeds where the embryo has attained the maximum size 

 permitted by the limits of the seed. The general subject 

 of the size and other features of embryos is handled in 

 Chapter XVIII. Here we deal only with those embryos, with 

 large, flat, more or less foliaceous cotyledons, that occupy the 

 length and breadth of the seed and lie usually between two 

 slab-like masses of albumen. A few of the leguminous seeds 

 used in this inquiry, viz. those of species of Bauhinia, Cassia^ 

 and Poinciana, have these characters ; and for most of them I 

 possess the requisite data for the embryo's weight-relation in 

 the pre-resting, resting, and swollen conditions of the seed. 

 In addition I have also materials for two euphorbiaceous plants 

 possessing albuminous seeds with similar embryos, viz. Ricinus 



