12 SCIENCE OF GARDENINCr. 



the root? of plants during the operation, arid assist iii 

 abstracting too much of their juices after tliey have been 

 removed. 



Plants convert the oxygen and carbon which they re- 

 ceive from the soil and air into carbonic acid, v-hich they 

 exhale at night. This being a deadly and danger ous gas 

 to human beings, plants or fiowers ai'e not considered 

 healthy in a sitting or bed room dm^iug the night. In rhe 

 day, they give off oxygen, especially in the morning, 

 which is reputed to render the morning air so fresh and 

 exhilarating. They are very useful in absorbing from the 

 air the carbon which is so injurious to animal life, and 

 they purify stagnant water in the same way. 



4:.— Water, 



This agent is composed of two parts of nydrogc-n ga^ 

 and one part of oxygen. In its simple stare, it i- mere- 

 fore not unfitted partially to s " u ^ 1 ui- E t - fi\ 

 rarely found thus free from some other mgredieur. : nd i- 

 capable of taking up all the various matters wluou i : 

 preserve and to develop vegetable life. ^ - . h . ~ 

 principal medium by which plants feed. 



AVater exists both in a liquid and a flu. . . l - 



as it is found in or upon the earth or in t..^ ruui, cohere. 

 It is always more or less naturally present m s:u-. rtud is 

 chscharged from the atmosphere, to which it travels 'V 

 means of evaporation, in the form of rain, .v, ,v: 

 "Without water, vegetables w^ alJ - e ' ' 1 

 therefore be supplied when it - i v ^ 



such plants as are kept in an -i ite. lue soil in 



which plants grow should I :.v lunsr, but not 



wet. In extremely wet soils, taere can never oe sumeienr 

 heat or air, and the vessels of planes placed in_ tiiem wi.l 

 soon become turgid and diseased. This is tiie basis of 

 all draining, whether in the narur.d ground, or in pots. 



A great variety of nutritive matters are conveyed by 

 nature to plants through the medium of water, and may 

 be applied artificiall}' by the same means. As only Invaias 

 can be absorbed, nothing that will not dissolve in tiiem 

 can be expected to enter the plant, or do it a particle of 

 good. 



