386 



Plant Physiology 



may be connected with the conditions in which the food 

 substances are stored in the seed, with the development of 

 injurious substances which lead to undesirable transfor- 

 mations, or with the continuance of activity after the 

 seed should have attained practically a dormant condi- 

 tion. 



Moreover, immaturity has a tendency to lessen the 

 keeping quality of most seeds, and many of the. shrunken 

 seeds upon the market, frequently met with in the case of 

 alfalfas and clovers, are due to their immaturity at the 

 time of harvesting. Apparently it is a general rule that 

 the sooner immature seeds are sown the more vigorous 

 will be the plants which they are able to produce. In 

 other words, a gradual deterioration takes place in stor- 

 age, but more promptly than in the case of well-matured 

 seeds. Extensive experiments in determining the effect of 

 maturity upon vitality as exhibited by germination tests 

 were carried out by Hellriegel. In the case of rye the 

 seeds were harvested at four different stages, and the 

 following table indicates the relative condition of ripeness 

 and the percentage of germination from such seeds, which 

 were subsequently treated alike with respect to drying 

 and storage : 



