PROPAGATION BY MEANS OF SEEDS AND SPORES 19 



usually 3-inch stuff. This shed screen is oftenest used for the 

 protection of tender plants, but it affords an exceedingly use- 

 ful and convenient place for 

 the storage of pots and boxes 

 of slow-germinating seeds. A 

 more elaborate shed screen, 

 made of lath or slats, and con- 

 taining Seed-beds edged with FIG. 10. Shed screen for seeds and 



boards, is shown in Fig. 11. plants. 



Various frames and covers are employed for indoor seedage, 

 designed to regulate atmospheric moisture and to control 

 temperature. They are more commonly employed in the 

 growing of cuttings, and are therefore described in Chapter V. 



Requirements of temperature 



Variations in temperature exercise less influence on seeds 

 than variations in moisture. Yet it is important that the ex- 

 tremes of temperature be not great, especially in small, delicate 



FIG. 11. Large shed screen, with seed-beds. 



or weak seeds. Seeds will endure greater extremes of tem- 

 perature when dry than when moist. This indicates that 

 germinating seeds must be kept in a relatively uniform tem- 

 perature. For this reason it is poor practice to put seed-boxes 

 in a window in full sunlight. Partial or complete shade serves 



