126 Propagation of Plants hy Cuttings. 



tissue at the lower end. Has this been produced solely from 

 the stored-up sap ? All the sap that existed in the cutting, 

 could not have formed such a mass of matter as we frequently 

 find accumulated at the base of very small cuttings. In this, 

 as in the case of bulbs, it is evident that the roots are not 

 formed exclusively from the stored-up sap. 



Further, — to show the futility of the opinion, that the 

 emission of roots is dependent upon elaborated sap, let us 

 look to the conditions under which a cutting with leaves, — 

 supposed to be under good management, — is usually placed. 

 We find it closely covered with a bell glass, and shaded from 

 light, and instead of giving it the benefit of a little fresh air 

 occasionally, the water required to moisten the soil is applied 

 outside the glass, and the latter will not be removed for weeks 

 together. The fact of roots being formed under these condi- 

 tions is a convincing proof, that it is not through the agency 

 of leaves, as will be seen from the following extract : — 



"It is from the continued assimilation of the elementary 

 constituents of plants, that new products result for the for- 

 mation of woody fibre, and all solid matter of a similar 

 composition. 



" This assimilating process is principally carried on in the 

 leaves, or occasionally in the young green bark. 



" To enable the leaves to perform their functions, they must 

 be exposed to light and air, especially to air in motion, for 

 without these be allowed to act upon them, they cannot exer- 

 cise their power of assimilation." 



We see from the above, that leaves confined under a bell 

 glass and shaded from light, cannot perform their functions, 

 and of course, cannot benefit the cuttings, nor remain long 

 in a healthy state, consequently they ought to be exposed 

 to as much light and air as their altered conditions will per- 

 mit, and bell glasses dispensed with as far as possible, as their 

 use is only substituting a greater evil to counteract a lesser. 



Scientific research has failed to discover the true nature of 

 the chemical changes and transformations that are constantly 



