PROPAGATION BY MEANS OF SEEDS AND SPORES 17 



stocky under it. It is better to use brush or lath screens if pro- 

 tection is desired ; or fine litter, if free from weed seeds, may be 

 employed. In most cases, however, screens will not be needed 

 by celery and similar seeds if the ground is in the proper con- 

 dition so that it will neither bake nor dry out quickly, and is 

 well firmed at planting time, and if the seeds are sown early 

 before hot dry weather comes. It is always advisable, never- 

 theless, to place the beds for slow and small seeds where they 

 can be watered occasionally and where there is protection from 

 strong winds and perhaps more or less protection from sun. 

 Plants much protected from sun, however, may be burned and 

 sometimes killed when transplanted to the field unless they 

 have been "hardened off ' : 

 before transference. 



Many kinds of screens are 

 in use to prevent the drying 

 out of small seeds in out- 

 door seedage and to protect 

 the young seedlings. These 

 are used also in the shad- 

 ing of cuttings. The com- 

 mon lath screen (Fig. 7) is FIQ 7 Lath gcreen 

 the most useful for general 



purposes. It is simply a square frame made from common 

 laths laid at right angles in a double series. The interstices 

 between the laths are equal in width to the laths themselves. 

 These screens are laid horizontally on a light framework a 

 few inches above the seeds. The passage of the sun constantly 

 moves the shadows over the bed, and sufficient shade is afforded 

 while thorough ventilation is assured. This and all other 

 elevated screens are useful in shading and protecting the young 

 plants as well, but when used for this purpose they are mostly 

 raised a greater distance above the beds. A brush screen, 

 consisting of a low frame covered with boughs, is often used, 



