118 PJnjsiological Pi-edetennuKition 



Kinzel(45) in his monograph on the influence of light upon seed germina- 

 tion emphasises the importance of the local origin of the seeds of Poa 

 pratensis with regard to their light-sensitiveness in germination. His 

 numerous experiments with seeds of Poa pratensis from different regions 

 show that every degree of light-sensitiveness may exist independently 

 of after-ripening, which occurs during storage. Seeds from plants of the 

 same original stock growing in different regions, when tested, showed 

 various degrees of light-sensitiveness in their germination. In one case 

 Kinzel {I.e.) with Poa pratensis was able to show that, even in the same 

 locality, different climatic conditions during maturation exert a marked 

 effect upon the light-sensitiveness of the resulting seeds. Seeds from 

 the crop matured in bright sunny weather at Munich in 1906 showed 

 themselves extraordinarily sensitive to the deleterious effect of blue 

 light; on the other hand, the seed-crop from the same original stock of 

 seed matured in dull rainy weather at Munich the following year showed 

 scarcely any sensitiveness to the harmful effects of these rays. 



Ottenw{Uder(58), working on the effect of light on germination of seeds 

 of Epilohiuni hirsutinn and other plants, found that the age and oiigin 

 of the seeds modified his results considerably. 



The environmental conditions which obtain during the maturation 

 of the seed are undoubtedly of great importance (cf. Von Lochow(48)). 

 Excessive moisture may hinder the gradual ripening processes and thus 

 affect the conditions under which food-reserves are stored in the seed, 

 and such effects may become evident in the plants produced from these 

 seeds. Duggar (I.e.) mentions these possibilities, but critical work on the 

 subject seems to be non-existent. 



It is possible that the effects of soil and climate resolve themselves 

 into a question of the degree of maturity reached by the seed at the 

 time of harvesting. 



B. Size of Seed as an Index of Parental Conditions 



AFFECTING " POTENTIALITY." 



Under this first category of parental conditions and their effect upon 

 the capacity of the seed for producing plants of greater or less vigour, 

 we deal next with the influence of the size of the seed upon the resulting 

 plant. This question has received more attention by both practical and 

 scientific workers than the less obvious, but equally important, factors 

 alluded to above. 



It is obvious that aiiv sninplo of seed can be graded according to 



