ON THE AMOUNT OF MOISTURE ABSORBED BY PLANTS. 195 



larger supply of this very necessary element, than they have the power 

 to consume, otherwise they will soon assume a sickly appearance, and 

 their roots become black and rotten by stagnation. And again in 

 making a selection for window culture, the generality of such plants 

 ought to be rejected, as in such situations dust is mostly generated, 

 which soon chokes up their digestive organs, and renders them in- 

 adequate to perform their functions; under which circumstances it is 

 impossible to keep the plants long in a healthy condition. In regard 

 to the state of the atmosphere, much also depends. If it be highly 

 charged with moisture, the exhalations of watery particles from the 

 surface of the leaves, will be necessarily impeded, and therefore the 

 absorption by the roots, as the one is always in proportion to the 

 other. And this is the reason why cuttings strike much more freely, 

 and certainly in a moist atmosphere, than in a dry one. In the former 

 case the quantity of fluid exhaled is so small (particularly if the at- 

 mosphere is confined), as not to exceed the quantity imbibed by the 

 severed ends of the young shoots, whereby an equilibrium is estab- 

 lished, and the life of the individuals sustained till such time as they 

 have made roots of their own; whilst in the latter, the quantity 

 passed off is so great in proportion to that taken up by their cut ends, 

 that their leaves soon become flaccid and dried up, and the cuttings 

 not unfrequently die. And should they even overcome the shock 

 caused by this undue demand upon their crippled energies, they will 

 have made less progress, and be in a much worse condition at the end 

 of three months, than they would have done at the end of three weeks, 

 had due attention been paid to their constitutional wants. The reason 

 why sun-light so greatly accelerates the amount of moisture sucked up 

 by the roots of plants, is due to its influence over the leaves, whose 

 breathing pores or mouths it causes to open to the widest extent, and 

 consequently facilitates the liberation of those aqueous particles which 

 are ever being evolved during the process of elaboration. Under such 

 circumstances, therefore, a plentiful supply of water is indispensable, 

 or the drooping of the plants will be the consequence ; and even this 

 will be insufficient in the case of newly-planted and weak subjects, 

 which, in addition to plenty of water, should have the scorching rays 

 of the sun partially intercepted by some kind of shading, as thin gar- 

 den-mats, nets, boughs of trees, &c, as circumstances may suggest. 

 Should the above remarks meet with your approval, they will be 



Q 2 



