200 Friucipl.es of Plant Culture. 



weeks, aud then be thoroughly washed " before being em- 

 ph:iye(l for cuttings. The same sand sliould be used for 

 but one lot of cuttings, as a rule, for it is liable to become 

 infeste<l with fungi that may work liavoc with cuttings 

 placed in it. 



369. Methods of Controlling Humidity. Where moist- 

 ure needs to be controlled with especial care, as in prop- 

 agating delicate plants from green cuttings, or in herba- 

 ceous grafting (393), the planted cut- 

 tings or the grafted plants are often 

 covered with bell-jars. To guard 

 against sudden fluctuations in temper- 

 ature, a larger bell-jar is 

 sometimes placed over a 

 smaller one. By means 

 of a bell-jar with a tight- 

 fitting ground plate, 

 evaj)oration may be 

 wholly j)revented from 

 cuttings or plants, if de- 

 sired. Propagating beds 



ttTare often covered with 

 glazed sash, in addition 

 to the glass roof of the house, to assist in maintaining a 

 moist atmosphere about the cuttings (Fig. 96). 



For convenience, we separate propagation by cuttings 

 into two divisions, viz., propagation by cuttings from 

 dormant and from actire plants. The requirements of 

 these two classes differ in some respects. 



a — Propagation by cuttings from dormant plants. 



370. The Time to Make the Cuttings. We have seen 

 that plant processes may not be wholly suspended during 



Fig. 96. Propagating bed covered wi 

 glazed sash. 



