ON PROP A GA TION B Y CUTTINGS. 219 



found by long experience greatly to facilitate the rooting of such cut- 

 tings, probably by increasing the surface by which absorption of 

 moisture takes place, and at the same time ensuring only a moderate 

 supply of moisture, and perhaps creating a greater demand for the 

 action of the leaves to cicatrize the wound with granular matter. When 

 cuttings are tardy to strike, and have callosities formed, heat has a power- 

 ful effect in causing them to root. Those that have stood months, with- 

 out any appearance of rooting, will strike in a few days in a strong heat. 



Treatment of Cuttings from the time they are made till they are planted. 

 In general, cuttings are no sooner made than they are inserted in 

 the soil where they are to remain till they strike root. If cuttings of 

 Dryandra, some Banksias (B. integrifolia, B. Baueri, B. media, B. 

 Caleyi, &c.), most of the long-leaved Acacias (A. longissima, A. pen- 

 dula, A. brevifolia, A. glaucescens, A. longifolia, A. micracantha, &c.), 

 and some sorts of Diosma (D. dioica, formosa, and umbellata), be stuck 

 in the earth immediately after being taken from the parent plant, the 

 inner bark will become black in from fourteen days to four weeks, and 

 the cutting will perish. This phenomenon appears to be in close con- 

 nexion with the form of the leaves of these plants, as those of the 

 Acacias have very small stomata, while those of the Dryandras have 

 none at all In their stead, on the under side of the leaves of the 

 latter plants are small dimples, lined with short hairs, which the 

 Diosmas also possess. Now, as the crude nourishing matter is drawn 

 up through the open wood in its existing state, and received by the 

 cutting, while the spongioles of the roots only imbibe it in a very thin 

 solution, it appears that the above-named plants, on account of the 

 peculiar formation of their leaves, cannot elaborate in any great 

 quantity this gross nourishing matter ; and hence arise stagnation of 

 the juices, and the before-mentioned appearances. The good effect of 

 leaving these cuttings lying, and thus interrupting the growing process, 

 appears to be the prevention of the superabundant rise of the crude 

 nourishing matter ; and this is the more probable, as it is usual, for 

 the same purpose, to rub over the section with a piece of clay. 



Cuttings of succulent, or fleshy, plants must also lie for a time before 

 planting, and on no account in a moist atmosphere, that the surface of 

 the cut may be sufficiently dried. The species of the families Melo- 

 cactus, Echinocactus, Mammillaria, Opuntia, Cereus, &c., have an ex- 

 tremely thick bark, and a fine epidermis, with very few stomata ; on 

 which account the process of evaporation is so slow, that they remain 

 alive for a long 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 are generally produced on the section between 

 the wood and the bark. The other succulent and fleshy plants, such as 

 the Aloe, Haworthia, Seinpervivum, Mesembryanthemum, Crassula, Plu- 

 mieria, and its congeners, as well as all the Cacti, which form side roots, 

 may be watered as soon as they are planted. Lastly, plants with milky 

 juice require similar treatment, as they are equally liable to damp off. 



