Propagation of Plants hy Cuttings. 125 



assimilation are absent, (as is frequently the case,) roots 

 will not be formed at all. 



We know, however, that both these inferences are errone- 

 ous, and more especially with regard to the latter, from the 

 fact, that roots are produced in abundance Avithout the aid 

 of leaves, and this certainly could not be the case, if the 

 nodules that are formed previous to the emission of roots, 

 were produced by any safe, elaborating process. Although 

 we allow that the young bark of some plants, does, under 

 certain conditions, perform the same functions as the leaves, 

 it is only an exception to a general rule, and can have little 

 effect, either for good or evil on the subject in question. We 

 cannot, therefore, regard the above argument as giving a 

 satisfactory explanation of any superiority possessed, or ad- 

 vantage to be gained, by retaining leaves on cuttings. 



Leaves are not absolutely necessary for the formation of 

 roots. Instances have come under my own observation, of 

 bulbs doubling their size and filling a large space with roots, 

 when covered with four or five inches of soil, without pro- 

 ducing a single leaf; and every gardener is aware of the ben- 

 eficial effects resulting from the application of a genial 

 warmth, (bottom heat,) to the roots of plants, which is nei- 

 ther more nor less than getting the roots, as it were, a stage 

 in advance of the foliage. On the same principle, unhealthy 

 plants, as camellias, oranges, &c., are resuscitated by keeping 

 the roots warm and the tops cool, to ensure a healthy and 

 vigorous action of root, previous to exciting the stem and 

 branches ; and this is often done after the plants are entirely 

 divested of leaves. 



There are others, who do not ascribe so much influence to 

 the leaves, but assert that the rootlets are produced from the 

 stored-up sap existing in the cutting at the time it is planted. 

 Acting upon this supposition, they are careful in keeping the 

 soil moist, and covering the whole closely with a glass, pre- 

 venting communication with the external air, in order to avoid 

 mechanical evaporation. This may seem plausible enough, 

 but if we insert a deciduous cutting into moist earth, we will 

 find, in the course of a few weeks, a mass of newly formed 



