THE THREE CONDITIONS OF THE SEED 47 



COMPARISON OF THE SHRINKING AND SWELLING RATIOS OF THE SEEDS 

 OF CANAVALIA ENSIFORMIS UNDER DIFFERENT CONDITIONS. 



Those cases where seeds of the same species at times 

 display much diminished swelling capacities, as expressed in 

 swelling ratios considerably below the average and outside the 

 ordinary range of variation, now claim our attention. Such 

 cases are peculiar to impermeable seeds, and occur when the 

 shrinking process is incomplete, less water being required for 

 germination, since less than the normal amount is lost in the 

 shrinkage. This is a point of considerable importance, and 

 one on which much of my work has been concentrated, since 

 it supplies the key to one of the principal positions maintained 

 in these pages. We get here our first glimpse at the signifi- 

 cance of impermeability, and we perceive how it comes about 

 that both permeable and impermeable seeds may be found in 

 the same species. 



Very interesting indications in this direction are sup- 

 plied by the seeds of Guilandina bonducella, and I will briefly 

 state the general results of numerous observations made 



o 



in Jamaica. When we open the full-grown green pods 

 of this plant we find two kinds of soft green pre-resting 

 seeds : 



(a) Yellowish green soft seeds, about 100 grains in weight 

 and 25 to 27 millimetres in diameter, which represent 

 the maximum development in size and weight of 

 the pre-resting seed before the shrinking process 

 commences. 



Third, to the 

 great diminu- 

 tion of the 

 swelling 

 capacity 

 caused by 

 the deficient 

 shrinkage of 

 impermeable 

 seeds as 

 illustrated, 



(a) by Gui- 

 landina 



bonducella, 



