1 98 Principles of Gardening physiologically considered. 



and the callus is not cut away, no roots are made, and the 

 cutting often remains several years without dying. 



In the use of beds heated by manure great circumspection is 

 necessary ; for the cuttings should neither be exposed to the 

 exhalations arising from it, nor immediately stuck in warm 

 sand or charcoal ashes (tan and sawdust, on account of the 

 insects lodging in them, are not so desirable). About eight 

 davs should, therefore, elapse before any thing is put in the bed ; 

 and bv turning over the sand, &c, the noxious vapour will be 

 diminished : the pots are then to be placed at first only on the 

 bed, and not plunged till the heat is diminished. As soon as 

 the bed has cooled, another must be made; for, when this is 

 neglected, not only those which have formed a callus make no 

 roots, but many that had formed roots, by the excitement of the 

 heat, become sickly. Plants that root easily thrive best in a 

 bed moderately warmed with leaves, on which, instead of the 

 sand and charcoal ashes, earth is placed, and the cuttings set in 

 it. Treated in this manner they display much greater activity 

 than when stuck in pots, so that, in the course of a few weeks, 

 shading and excluding the air are less necessary. To reap the 

 same advantage with plants that are more difficult to root, boxes 

 1^ ft. wide, and from 8 in. to 1 ft. high, are used. These must 

 have holes at the bottom to drain off the water, the bottom 

 covered with sherds, and only so far filled with earth as to leave 

 room for the boxes to be covered with glass without the 

 cuttings being pressed down by it. When the bed becomes 

 cool, they can easily be removed into a fresh one ; and in this 

 way many of the most difficult-rooting ti'opical plants, such as 

 Dillenia speciosa, Coccoloba pubescens, C. macrophylla, the 

 species of Ix6m and Banisterm, &c, grow well. Propagating 

 houses, with beds made on purpose for heating, are always the 

 most serviceable. When one of these beds is made, the trouble 

 of always forming new ones is obviated ; the cuttings, which can 

 have an equal warmth of soil constantly maintained, are not ex- 

 posed to the noxious vapours of the dung; and the greatest use 

 of such a bed is, that the cultivator is not bound to any one parti- 

 cular season, as any time of the year will serve for propagating. In 

 constructing a house for this purpose, which should only becovered 

 with glass at the top, particular care should be taken that the heat 

 should be equally directed over every part of the bed, and increased 

 or diminished by means of valves ; and the sand and charcoal 

 ashes always kept damp, so as to preserve a sufficient moisture in 

 the house from the vapour arising from it. For heating, the 

 most suitable method is by water, as that sort of warmth is mone 

 suitable and beneficial to the plants. Heating by pipes, with 

 particular precautions for the equal distribution of the heat, 

 which we leave to the judgment of our readers, is also suitable; 



