THE THREE CONDITIONS OF THE SEED 53 



(9) Additional proofs of the mechanical nature of the swelling process 

 are indicated as follows : 



(a) By the fact that when a seed on the eve of germination is 



dried, it returns approximately to its original weight as a 

 resting seed. The results of a number of experiments on 

 leguminous seeds are given, and it is shown that seeds fall 

 short of or exceed the original weight according as they were 

 in the first place permeable or impermeable (p. 30) ; 



(b) By the fact that the weight-relations of coats, kernel, albumen, 



and embryo are much the same in the seed dried after swell- 

 ing for germination as they are in the resting seed ; illus- 

 trated by examples (p. 31) ; 



(c) In the ability of the embryo in many pre-resting seeds to pass 



at once to germination without the intervention of the 

 resting stage, such embryos being potentially viviparous 



(P- 32). 



(10) Neither the large, soft pre-resting seeds nor the seeds swollen for 

 germination are in a condition of saturation (p. 33). 



(n) The shrinking and swelling ratios are then more closely con- 

 sidered (p. 34). 



(12) The views of Dr Nobbe (p. 34). 



(13) The difficulties of the subject, and the necessity of confining the 

 discussion of principles to one family, namely, the Leguminosae 



(P- 35)- , 



(14) The constancy of the shrinking and swelling ratios of normal 

 resting seeds of the same species is then shown (p. 35). 



(15) But the contrast, as exemplified by the swelling ratios, is great 

 between difFerent species, whether in groups or in individuals. Thus, 

 the Cereals with a swelling capacity of not over 60 per cent., and the 

 Leguminosae with a capacity ranging between 90 and 2OO per cent., 

 represent the minimum and maximum groups. That leguminous 

 seeds possess the highest capacity for absorbing water when preparing 

 for germination was stated long since by Nobbe. The contrast 

 between individual species is displayed by the seeds of Ricinus communis 

 and of Guiland'tna bonducella, the first adding only one-third to their 

 weight, and the last trebling their weight when swelling for germin- 

 ation. Seeds that possess a very low swelling capacity, for instance, 

 below 20 per cent., are probably on the borderland of vivipary 



(PP. 3 6 ~3 8 )- 



(16) The reasons of the great range in the swelling capacities of 



difFerent seeds are then considered, that is to say, why the seeds of some 

 plants absorb much water and others very little in swelling for germina- 

 tion. After endeavouring to ascertain whether there is any connection 

 between this great variation, and certain conspicuous difFerences in 



