878 LEAVES UNWILLING TO FORM BUDS. 



The last point to which attention need be directed is the 

 necessity of exposing leaves to the free influence of light. In 

 natural conditions, a leaf does something more than feed — ^it 

 breathes. The one act is as needful as the other. In the light 

 respiration goes on freely ; in the dark, it is suspended, or at 

 least is much impeded. But in sunlight a leaf not only 

 breathes, but loses water — a circumstance of no. importance 

 to it whilst upon its parent plant, because all loss is then made 

 good from instant to instant, through the veins which pass out 

 of the stem. Separated from its natural source of supply, the 

 condition of the leaf is entirely altered; and it cannot be 

 expected that the loss occasioned by evaporation should be as 

 equally and instantaneously compensated. The only way of 

 meeting this difficulty is by covering leaves with bell-glasses, 

 whose edges are. sunk in the damp sand or earth, in which the 

 leaf is to be struck. In this way, the leaf will always be in 

 contact with moist air. Under a bell-glass the perspiration of 

 a leaf in sunlight is then so much diminished as to be of no 

 importance, because, if the leaf is losiag water, it is also 

 absorbing it, and this as copiously as its nepessities demand. 

 It may therefore be exposed to the conditions favourable to its 

 breathing, without danger of injury. 



The great objection to employing leaves as a means of pro- 

 pagation consists in their unwillingness, in many instances, to 

 form a bud as well as roots. A leaf of Hoya carnosa has been 

 known to remain without change for nine or ten years, although 

 it produced roots. The leaves of roses - strike freely, but will 

 not bud. These peculiarities belong to the nature of species, 

 and are not susceptible of explanation. 



The following is Mr. Neumann's practical account of the manner in 

 which his experience aa a propagator teaches him to proceed with 

 leaves : — 



"A single leaf out near the stem and planted, is sufficient, in. 

 some plants, to produce new individuals. The leaves intended for this 

 operation ought not to be pulled off the stem ; there is no need of 

 taking away the eye which showa itself at their axil ; in this method of 

 striking hy cuttings it is not the eye which developes itself, as many 

 people imagine ; the effect which takes place is similar to that produced 

 when cuttings are struck from the branch of Abies. It is upon the 



