LONGEVITY 71 



show. Sturtevant mutilated the kernels of a FUnt Corn and the 

 seeds of Beans and found the percentage of germination much 

 reduced in each case. 



Seeds collected while immature usually show a low percentage 

 of germination and their embryos grow slowly. In the case of 

 Rye, seeds have been harvested at different stages of their devel- 

 opment and, after similar treatment in respect to drying and 

 storage, the percentage of germination and vigor of embryos de- 

 termined. In the milk stage five per cent germinated, while in 

 the dry ripe stage eighty-four per cent germinated. The embryos 

 of the dry ripe seeds were much more vigorous in growth than 

 those of the immature seeds. Tomato seeds, while still green and 

 not more than two-thirds the weight of mature seeds, may be 

 germinated, if properly cured, but the plants produced are likely 

 to be weak. The germination of unripe seeds has been given 

 considerable attention by Sturtevant, Arthur, and Golf.^ 



Experiments ^ with seeds of the Radish, Sweet Pea, Cane, Rye, 

 Oats, and Cotton have shown that better stands in the field and 

 more vigorous and better yielding plants are secured by using 

 only the heavier seeds. 



The vitality and vigor of seeds depend very much upon the 

 methods of storing. Seeds are more easily killed by extremes of 

 temperature when wet. Seeds stored where there is considerable 

 moisture may start to germinate, and then die. Seeds, massed 

 together before they are well dried, become moist and often so 

 warm that the embryos are injured. On the other hand, when 

 stored in rooms where the air is warm and extremely dry, seeds 

 may lose moisture so rapidly that the embryos are killed. A 

 storage room should be cool but above freezing, and dry, although 

 not excessively dry. Until the seeds are well dried, they should 

 not be massed together, but so arranged that the air can circulate 

 about them. Thus methods of storing seed Corn and other seeds 

 must reckon with a number of factors which affect the vitality 

 and vigor of seeds under storage 'conditions. 



Longevity. — The vitality and vigor of seeds depend much 

 upon their age . Seeds in excellent condition and stored by the best 

 methods finally lose their vitality, due to the coagulation of their 

 protoplasms, too much drying, or some other factor not under- 



1 American Naturalist, pp. 806 and 904. 1895. 



2 Farmers' Bulletin 678, U. S. Dept. of Agriculture. 



