296 BELL-GLASSES EMPLOYED. 



uniform degree of humidity in the atmosphere breathed by the 

 cuttings. It is generally necessary to leave one or more leaves 

 upon a cutting, in order to generate organizable matter, and to 

 assist in the formation of roots ; but this is a delicate 

 operation, for, if the leaf is allowed to suffer by excessive 

 perspiration, the cuttings must necessarily perish. To main- 

 tain "a steady saturated atmosphere around a cutting stops this 

 danger, and hence the use of a bell-glass. A double glass has 

 even been recommended ; but, if this precaution is of any value, 

 it must be, not because it preserves an even temperature, which 

 is injurious rather than useful, but because it prevents con- 

 densation upon the inner bell-glass, and the consequent 

 abstraction of atmospheric moisture, and probably acts at the 

 same time as a kind of shade. 



Notwithstanding the precaution of covering cuttings with a 

 bell-glass, shade is also necessary, as a further security 

 against perspiration; for light acts as a specific stimulus, 

 whose effects are very difficult to counteract. It must, 

 however, be employed with great caution ; for, if there is 

 not light enough, the leaves attached to the cuttings cannot 

 form that organizable matter out of which roots are produced. 



All gardeners know that the root end of a cutting should be 

 close helow a leaf-bud ; this is to facilitate the emission, of 

 roots by the buds, which emission must necessarily take place 

 with greater or less difBiculty in proportion as their exit is 

 facilitated or impeded by the pressure of bark on them. 



A mode of overcoming some of tlie practical difficulties attending the 

 propagation of plants by cuttings has been described by Prof. Delacroix, 

 of Besangon. TMs gentleman states that he, some years since, con- 

 ceived the idea of insuring the success of cuttings, by putting the lower 

 end in water, and the middle in earth, a circular incision being made 

 between the earth and water. This was not attended with all the 

 advantages he expected, but it led to the discovery of the following 

 plan, which he designates a simple, economical, and certain mode of 

 propagation. His process is described in the following words : — 



"My cutting is placed entirely under-ground, so as to form a 

 subterranean curve, of which the convexity is uppermost, the very 

 middle of the curve being on a level with the surface of the soil. At 

 this middle point there must be a good eye, or a small shoot. In this 

 way the whole length of the cutting is protected by earth, and the 



