98 PEOPAGATION OF PLAKTS. 



severed cells of the stems, leaf-stalks, and also through 

 the stomata, -under varying conditions and circumstances. 



Ur. G. Hartwig, in " Harmonies of Ifature," says : 

 " The stomata are destined to admit air, not water, which 

 by drenching the leaf would entirely interrupt the process 

 of respiration." But Hugo von Mohl, a very able inves- 

 tigator in the structure of plants, has shown very clearly 

 that the stomata open in the presence of moisture and 

 close in a dry atmosphere, as may be readily verified by 

 any one who will examine them under a glass of high 

 magnifying power. 



Gardeners utilize this power of severed cells to absorb 

 moisture and nutriment, especially in propagating plants 

 by cuttings of the young and immature parts, or by what 

 are technically termed "green cuttings." In employing 

 such cuttings it is well for the propagator to keep in 

 mind the fact that the severed and exposed cells at the 

 base of the cuttings cannot resist the noxious properties 

 which may be presented to them in liquids with the same 

 power as roots, hence the greater necessity of selecting 

 pure and innocuous materials in which to plant the cut- 

 tings while producing roots. I have kept the roots of 

 such coarse celled and rank growing plants as the Calla 

 {Eichardia) submerged in a solution of Madder and other 

 vegetable dyes for weeks at a time without detecting any 

 indications of their absorption by the plants, although 

 the outer bark, or epidermis, of the roots and smaller root- 

 lets were soon colored ; but if a leaf -stalk of one of these 

 plants is cut ofE and the severed end set in the dye, some 

 of the coloring matter will soon be absorbed and easily 

 traced upward to a greater or less distance. 



That theimbibtion of liquids through the roots, as well 

 as by the severed cells of a green cutting, is in part due 

 to leaf action can scarcely be questioned, but it is not the 

 cn^" force that aids in the ascent of the sap of plants, 

 for absorption will occur in the absence of leaves and even 



