The Seed in Plant Production 393 



water absorption. Again, in the case of a few seeds, it 

 seems to be established that the exclusion of oxygen is 

 the important factor. The resting spores of many fungi 

 are notably difficult to germinate until after a period of 

 rest, and it is quite probable that similar factors are con- 

 cerned here, especially through the deposition of some 

 resinous substance in the cell-wall. 



234. Effect of weight and size of seed upon vigor. 

 Since the weight and size of seed determine the amount 

 of food-material immediately available for the plantlet, 

 at the time of germination, it is to be inferred that these 

 factors might have some influence upon production. 

 Early experiments by Hellriegel, Wollny, Marek, and 

 others were favorable to the view that seed of greater 

 size and weight give generally more vigorous plants than 

 those smaller or lighter. Much additional experimental 

 work has been reported in recent years, and some of this 

 evidence should be considered with respect to a few crops. 



The problem is not so simple as it seems. Viewing the 

 matter from the standpoint of the factors readily recog- 

 nized, the effect of the accumulated food-materials is cer- 

 tainly to start the seedling off vigorously. If the coty- 

 ledons of the bean or pea are removed even during the 

 late stages of germination, the plants thus deprived of a 

 portion of their resources fall behind in growth. It is to 

 be expected that the final effect of this loss would depend 

 much upon the conditions subsequently encountered. If 

 the season is bad, or the soil poor, the seedling with more 

 potentiality in itself should be able to become established 

 more safely and quickly, and the advantage secured 

 might persist. Hellriegel supports the view that differ- 



