16 PROPAGATION OP PLANTS. 



plants, a more compact and systematic organization is 

 observable and the cell-walls toucli each other at one or 

 more points, permitting of the transmission of fluids 

 from one to another. While young the ceU-walls are so 

 thin that they allow of a rapid transmission of fluids and 

 gases> but when they reach a more mature condition the 

 walls become thick and rigid, but nerer entirely impervi- 

 ous to liquids, for even dead plants will absorb moisture, 

 and often assume the forms and colors which they pos- 

 sessed when alive. The restoration to apparent life of 

 various species of Lycopodiums, Mosses, and the well- 

 known "Kose of Jericho" {Anastatica MerocTiuntinc), 

 are familiar examples of this kind. But it is only while 

 the cells are young and contain protoplasm that they are 

 available for the propagation of plants under artificial 

 conditions. The propagator should keep this in mind, as 

 it will often he of assistance to him in selecting cuttings 

 and cions of plants for propagation. 



The Teansttdatiok op Flttids. — The inherent 

 power that cells possess of absorbing fluids and transmit- 

 ting them from cell to cell, is the process by which 

 nature enables plants to obtain nutriment from the 

 medium by which they are surrounded, whether it be 

 air, earth, water, or all of these combined. This trans- 

 ference of fluids from one cell to another, by a process of 

 transudation, is universal among plants, and while it may 

 be said that the energy displayed in the movement is 

 controlled by a physical law applicable to both animal 

 and vegetable membranes, still there is a vital force pres- 

 ent in the living tissues, of the origin or properties of 

 which we know but little. The operations of this force 

 or principle may be, as is generally claimed by vegetable 

 physiologists, purely mechanical, but that it does possess 

 an inherent power of selection, using certain material or 

 elements and rejecting others, can scarcely be doubted, or, 

 as Dr. Thayer has said, m a paper on Plant Life, that, 



