452 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



species of Acanthus ior example, such selection is unnecessary. Any 

 portion oi an internode may be used as a cutting. In such cases the 

 shoot-bud for extension is an entirely new formation from the callus, as 

 it is in coppice. 



There has been much discussion over the question — ought the 

 leaves at the base of^ the cutting to be removed or not? Some pro- 

 pagators remove them, others prefer to leave them. I know of no 

 definite comparative experiments bearing on the advantage of one 

 practice over -the other, but the practice of leaving them has these 

 advantages : 



(a) The cutting is saved the healing of the wound caused by 

 their removal. 



(h) The lower leaves sunk in the soil may root like the stem and 

 aid thereby water absorption. 



(c) The lower leaves will aid in the manufacture of food for the 

 cutting. 



In many cases retention or removal is probably of little moment, 

 but the choice might be critical in a particular species, and the point 

 ought, therefore, to be in the mind of the gardener. 



The place on the stem of the mother-plant where the severing cut 

 for the base of the cutting is made is of importance in some species. 

 It may make all the difference between immediate, belated, or no 

 success. Commonly the section is made at the node — nodal cuttings — 

 and for most plants this seems to be satisfactory. There are, however, 

 plants which propagate far more readily if the cutting be made through 

 an internode — internodal cuttings. 



Clematis may be cited in illustration. The common belief is that 

 species of this genus are difficult tO' strike, and propagation by grafting 

 and other methods is frequently adopted. They are really not difficult 

 to strike from cuttings if the cutting be made through an internode. 

 (Fig. 158.) Internodal cuttings may be struck within a fortnight. It is 

 otherwise if nodal cuttings are used. These callus well, profusely 

 indeed, but refuse to form roots either from the callus or from the stem 

 above it. Doubtless this has given rise to the widely spread belief that 

 it is difficult to strike cuttings of Clematis. 



Why there should be this difference between nodal and internodal 

 cuttings is one of the problems ol propagation which we have yet to 

 solve. 



It is well known that once callus-formation is started at the base 

 of a cutting it often continues until a large nodular ball is formed. 

 Some plants appear to possess this habit in a remarkable degree, and 

 it is no uncommon experience to read that the cuttings of certain 

 plants will callus freely but will not root, or only after so long a 

 period — a couple of years or more is not an unusual time — that the 

 patience of the propagator is exhausted before rooting occurs. . Lonicera 

 Hildehrandtii is a conspicuous example. (Fig. 159.) 



If the fact be appreciated that the primary impulse to callus- 

 formation is that of wound-stimulus, and that the stimulus spreads 



