170 INGKEASING EXOTIC PI,ANTS FROM CUTTINGS. 



time without receiving external nourishment. The dried cuttings of 

 these plants, therefore, are generally planted in dry earth, and set in a 

 bed or house filled with warm air, and are not watered till they have 

 formed roots from the nourishing matter accumulated in themselves. 

 The roots can scarcely ever penetrate the thick bark, and are produced 

 between the wood and the bark. In some of the Opuntia and Cereus 

 species, however, they come out of the bark at the side. The other 

 succulent and fleshy plants which form side roots, such as the Aloe, 

 Haworthia, Sempervivum, Mesembryanthemum, Crassula, Plumieria, 

 and its congeners, as well as all the Cacti, are watered as soon as they 

 are planted. Lcistly, plants with milky juice also require similar 

 treatment, as they are equally liable to damp off. 



As soon as a part of one of these plants is cut off, the milky juice 

 exudes in great quantities, covers the whole surface of the cut, and 

 hardens like caoutchouc, by which the vessels are all stopped up, and 

 the ascension of the moisture prevented. Cuttings of Ficus, and the 

 dry roots of Euphorbia, are put in water, where they remain twenty- 

 four hours before they are put in the earth. The same end is also 

 attained when they are put in dry sand immediately after being cut, 

 and afterwards the sand and the milky juice cleared away. Ouly the 

 succulent and very milky Euphorbias must lie for some time. 



Although it is proved by the above that the cutting receives as 

 much moisture through the face of the cut as it loses in ordinary cir- 

 cumstances by evaporation, yet no sooner is it placed in verj' 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 waterj' par-» 

 tides are lost through evaporation than are raised in the body of the 

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

 account, hot-beds and houses prepared on purpose for propagating are 

 used, in which the outer air is excluded, a moist temperature main- 

 tained, and, in very warm sunshine, a dense shade is given. Bell- 

 glasses are placed over the more diflicult-rooting cuttings, to protect 

 them from all external influences which might destroy them before the 

 made roots. Tiie most proper form of bell-glass is that which gra- 

 dually 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 dis- 

 advantage 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 purpose. 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 exten- 

 sive establishment, this operation requires much time, and thereforQ 



