ON PROPAGATION BY CUTTINGS. 



255 



addition split up for an inch or two, and the wound kept open with a wedge. 

 This has been found by long experience greatly to facilitate the rooting of 

 such cuttings, probably by increasing the surface by which absorption of 

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

 of moisture; and perhaps, creating a greater demand for the action of the 

 leaves to cicatrize the wound with granulous matter. See fig. 168, in which 

 a cutting of shaddock is not only slit up at the lower end at a, where it is cut 

 oflF immediately below a joint, but tongued or cut at the first joint at b. 



582. 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 ; but there are several 

 exceptions, as appears by the following extract from M. Kegel, already 

 quoted from : — As the crude sap in the cutting is not raised by endosmose, 

 but by the process of evaporation, care must be taken that the surface of the 

 cut does not become dry before being put in the earth, and air get into the 

 lower end of the vessels ; for, as soon as this takes place, only very strong 

 shoots are capable of drawing up moisture, as has been proved by the ex- 

 periments of various philosophers. The cuttings should therefore be stuck 

 in wet sand, if they cannot immediately be put where they are intended to 

 remain, although it were better to avoid this. If, however, they are such 

 as ought to lie a day or two, in order to insure success, such as some 

 banksias, acacias, &c., it ought to be in a damp place ; and the precaution 

 must be taken, if possible, to cut them again before planting. If cuttings 

 of Dryandro, some banksias (B. integrifolia, B. Baueri, B. media, B. 

 Caleyi, &c.), most of the long-leaved acacias {A. longissima, A. pendula. 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 connexion 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 cut- 

 tings 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. 



583. 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. They retain so many watery particles in 

 their cellular tissue, that, when this is neglected, the face of the cut soon 

 rots. The species of the families Melocactus, Echinocactus, Mammillaria, 

 Opuntia, Cereus, &c,, have an extremely thick bark, and a fine epidermis, 

 with very few stomata ; on which account the process of evaporation is so 



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