168 ELEMENTARY STUDIES IN BOTANY 



having been consumed by the embryo, which occupies all the- 

 space of the seed within the testa (Fig. 132). The food we 

 obtain from peas and beans, therefore, has been transferred 

 from the endosperm to the embryo (chiefly to the cotyledons, 

 which form the bulk of the embryo). 



The embryo is in a dormant stage ; that is, its protoplasts 

 are inactive. With the embryos in this condition, the 

 seeds are scattered, and may remain for a long time without 

 showing any of the ordinary signs of life. If stored in a dry 



FIG. 133. Seed-vessel (fruit) 

 of violet splitting into three 

 "valves" and discharging FIG. 134. Pods of a wild bean twisting in 



its seeds. After BAILLON. discharging seeds. After BAILLON. 



place, the period of dormancy may be very much prolonged, 

 but in ordinary cultivated plants, the best results are ob- 

 tained from seeds " planted " in the year following their 

 formation. The danger in keeping seeds too long is that the 

 embryos may deteriorate, and although the seeds look sound, 

 the young plants may not be able to grow. It is for this 

 reason that " seed-testing " has become a very important 

 business, to learn whether seeds offered for sale are capable 

 of " germination." 



It is evident that seed-dispersal and seed-germination are 

 the two important topics in connection with seeds in nature. 



