590 



FARxMERS' REGISTER. 



[Nolo 



posure of the spongioles to occasional dryness, and 

 a dry atmosphere. 



305. Tlie most ready nneans of counteracting 

 the evil consequences of an imperfect action of 

 the roots is by preventing or diminishing evapo- 

 ration. 



306. This is to he effected by rendering the at- 

 mosphere extremely humid. 



307. Tlujs, in curvilinear iron hot-houses, in 

 which the atmospiiere becomes so dry in conse- 

 quence of the heat, that plants perish, it is neces- 

 sary that the air should be rendered extremely 

 humid, by tlirovvinir water upon the pavement, or 

 by introducing steam. 



308. And in transplantation in dry weather, 

 evergreens, or plants in leaf, often die, because 

 the s'ponifioles are destroyed, or so \hr injured in 

 the operation as to be unable to act, while the 

 leaves never cease to perspire. 



309. The greater certainty of transplanting 

 plants that have been growing in pots is Irom this 

 latter circumstance intelliirible, 



310. While the utility of putting cuttings or 

 newly transplanted seedlings into a shady damp 

 atmosphere, is explained by the necessity of hin- 

 dering evaporation. 



XIII. Cuttings. 



311. When a separate portion of a plant is 

 caused to produce new roots and branches, and to 

 increase an individual, it is a cutting. 



312. Cuttings are of two sorts — cuttings proper- 

 ly so called, and eyes. ("319.^ 



313. A cuttintj; consists of an internodiuni, or a 

 part of one, with its nodus (59.) and leaf-bud. 



314. When the internodium is plunged in the 

 earth it attracts fluid from the soil, and nourishes 

 the bud until it can feed itself 



315. The bud, teeding at first upon the matter 

 in the internodium, gradually elongates upwards 

 into a branch, and sends organized matter down- 

 wards, which becomes roots. 



316. As soon as it has established a communi- 

 cation with the soil, it becomes a new individual, 

 exactly like that from which it was taken. 



317" As it is the action of the leaf-buds that 

 causes growth in a cutting, it Ibllows that no cut- 

 ting without a leaf bud wifl grow. 



318. Unless the cutting has great vitality and 

 power of forming adventitious leaf buds (119.), 

 which sometimes happens. 



319. An e>e is a leal-bud without an interno- 

 dium. 



320. It only differs from a cutting in having no 

 reservoir of food on which to exist, and in emit- 

 ting its roots immediately ti'om the base of the 

 leaf-bud into the soil. 



321. As cuttings will very often, if not always, 

 develope leaves before any powerful connection is 

 li)rined between them and the soil, they are pecu- 

 liarly liable to suffer from perspiration. 



322. Hence the importance of maintaining their 

 atmosphere in an uniform state of humidity, as is 

 effected by putting bell or other glasses over thein. 



323. In this case, however, it is necessary that 

 if air-tight covers are employed, such as bell 

 crlasses, they should be from time to time removed 

 and replaced, for the sake of getting rid of exces- 

 sive humidity. 



324. Layers differ from cuttings in nothing ex- 



cept that they strike root into the soil while yet ad" 

 heniigto the parent plant. 



325. Whatever is true of cuttings is true of lay- 

 ers, except that the latter are not liable to suffer by 

 evaporation, because of their communication with 

 the parent plant. 



.326. As cuttings strike roots into the earth by 

 the action of leaves or leaf-buds, it might be sup- 

 posed that they will strike most readily when the 

 leaves or leat-buds are in their greatest vigor. 



327. Nevertheless, this power is controlled so 

 much by the peculiar vital powers of different spe- 

 cies, and by secondary considerations, that it is im- 

 possible to say that this is an absolute rule. 



32S. Thus Dahlias and other herbaceous plants 

 will strike root freely when cuttings are very 

 young; and Heaths, Azaleas, and other hard 

 wooded plants, only when the wood has just be- 

 gun to harden. 



329. The former is, probably, owing to some 

 specific vital excitability, the force of which we 

 cannot appreciate; the latter either to a kind of tor- 

 por, which seems to seize such plants when their 

 tissue is once emptied of fluid, or to a natural 

 slowness to send down woody matter, whether tor 

 wood or not, which is the real cause of their wood 

 beincT harder. 



330. If ripened cuttings are upon the whole the 

 most fitted lor multiplication, it is because their tis- 

 sue is less absorbent than when younger, and that 

 they are less likely to suffer either from repletion 

 or evaporation. 



331. For to gorge tissue with food, before leaves 

 are in action to decompose and assimilate it, is as 

 prejudicial, as to empty tissue by the action of 

 leaves, before spongioles are prepared to replen- 

 ish it. 



332. For this reason, pure silex, in which no 

 stimulating substances are contained (silver sand) 

 is the best adapted for promoting the rooting of 

 cuttings that strike with difficulty. 



333. And for the same reason, cuttings with 

 what gardeners call a heel to them, or a piece of 

 the older wood, strike root more readily than such 

 as are not so protected. The greater age of the 

 tissue of the heel renders it less arjsorbent than 

 tissue that is altogether newly formed. 



334. It is to avoid the bad effect of evaporation 

 that leaves are usually for the most part removed 

 fi-om a cutting, when it is first prepared. 



XIV. Scions. 



335. A scion is a cutting (311.) which is caus- 

 ed to grow upon another plant, and not in earth, 



336. Scions are of two sorts, scions properly so 

 called, and buds. (354.) 



337. Whatever is true of cuttings, is true also of 

 scions, all circumstances being equal. 



338. When a scion is adapted to another plant, 

 it attracts fluid from it for the nourishment of its 

 leaf buds, until they can feed themselves. 



339. Its buds thus fed gradually grow upwards 

 into branches, and send woody matter downwards, 

 which is analogous to roots. 



340. At the same time the cellular substance of 

 the scion and its stock adheres (19.) so as to form 

 a com[)lete organic union. 



341. The woody matter descending from the 

 bud passes through the cellular substance info the 

 stock, where it occupies the same situation as 



