PROPAGATION BY SEEDS 45 



of the halves of the pod. In the squirting cucumber, the 

 least disturbance of the plant causes the cucumber to break 

 loose from the stem and shoot its seeds with considerable 

 force. 



57. Rest-period of seeds. In most cases, it would be 

 fatal to the life cycle if seeds were to grow as soon as shed, 

 because the young plants might be brought into growth at 

 the wrong time of year and so subjected to frost-injury or to 

 other unfavorable conditions. Nature guards against this by 

 causing the seeds to go into a resting period as well as by 

 requiring certain favorable external conditions before the 

 seed can germinate. Many seeds remain in the resting period 

 for a considerable length of time, others for a short time, while 

 a few have no resting period at all. 



58. Storage of seeds. Man has learned to preserve seeds 

 for certain lengths of time by providing them with conditions 

 which will keep them in a resting state without injury. 



Seeds with thin protective coats, including those of most 

 of the vegetables and cereals, permit of air drying and can 

 be preserved by storage in paper bags or boxes in a cool dry 

 place. The temperature should remain as nearly uniform as 

 possible, for if it varies, the growing power of the seed is 

 likely to be impaired. The best temperature for storing seeds 

 in temperate climates has been found to be between 60 and 

 70 degrees Fahrenheit, but there are exceptions; for example, 

 Indian corn keeps best in a temperature near the freezing 

 point. 



Seeds with thick hard coats, such as nuts and pits of stone- 

 fruits, keep best when 

 stratified. Stratification 

 consists in placing seed 

 and sand in alternate 



layers in boxes (Fig. 26) . FIG. 26. Stratification of seeds in box. 



The sand should be kept slightly moist but not wet. It must 

 be coarse enough to provide drainage, which should be facili- 



i 



