ON THE PROPAGATION OF PLiNTS BY CUTTINGS. 39 



cumstances by evaporation, yet no sooner is it placed in very dry air, 

 or in a draught, or exposed to the sun's rays, than a disproportion takes 

 place between them. When this is the case, more watery particles 

 are lost through evaporation than are raised in the body of the wood, 

 which is very easily perceived in fleshy-leaved plants. On this ac- 

 count, hot-beds and houses prepared on purpose for propagating should 

 be used, in which the outer air can be excluded, a moist temperature 

 maintained, and, in very warm sunshine, a dense shade can be given. 

 Bell-glasses should be placed over the more difficult-rooting cuttings, 

 to protect them from all external influences which might destroy 

 them before the made roots. The most proper form of bell-glass is 

 that which gradually tapers from the base to the top, as from glasses 

 of this shape the moisture, which adheres to the inside in the form of 

 drops, runs gradually off without the dropping so injurious to cuttings. 

 This disadvantage is found in all other forms more or less, such as 

 those that are round at the top, or cylindrical, with the top bluntly 

 truncated ; and also in beer-glasses, which are often applied to this pur- 

 pose. The most unsuitable glasses, which are, however, much used, 

 are those small at the base, and swelling out like a globe. 



The enclosed air under the glasses will soon lose its oxygen, 

 through the respiring process of the plants within, and also be vitiated 

 by other exhalations ; and, if it is not changed, it generates mould, 

 and the cuttings lose their fresh appearance. For this reason, the 

 glasses, if possible, should be daily ventilated and wiped ; or, what 

 is still better as it will entirely renew the air, dipped in a vessel of 

 cold water, and well shaken, so that too many drops of water may not 

 remain on the glass, although they are not so injurious to the cuttings. 

 In an extensive establishment, this operation requires too much time, 

 and therefore round holes, of about from half an inch to three-quarters 

 of an inch in diameter, should be made at the top of the glasses; and 

 these will prove very serviceable, if the pans stand on a warm plat- 

 form in the houses or beds prepared for the purpose. In small 

 gardens, where the cuttings are placed with other plants in the houses 

 on the bed or shelf under the windows, glasses without holes would 

 be preferable. 



The cuttings themselves should not be stuck too close together, and 

 all the leaves should be left on, which are essential for elaborating 

 the absorbed and deposited nourishment ; removing the lower leaves 



