CONVERSION OF THE FOOD OF PLANTS. 203 



water, another carries it, another uses it in cooking, another gets 

 rid of the waste, another obtains the solid food, another carries 

 the cooked provisions to all parts of the structure, another stores 

 up the superfluity, another builds additions to the edifice, whilst 

 another prepares to send out a colony, furnished with supplies of 

 food, and with everything requisite to begin life for themselves. 

 Now we have considered the separate parts of the establishment 

 we have inspected the pump, the conduits, the kitchen, &c. ; 

 the general economy of the whole remains to be reviewed. And 

 if we have seen a Wise Design in those, our ideas will be still 

 further elevated by this mode of viewing the subject. 



317. We have seen that the fluid absorbed by Plants consists 

 of water, in which are contained carbonic acid and ammonia; and 

 in which are also dissolved the various mineral substances, which 

 each species requires for its healthy existence, but which contri- 

 bute nothing to the formation of those peculiar organic substances, 

 that compose the vegetable tissues. The conversion of these 

 elements into the substances intended for the nourishment of the 

 plant, begins very low in the stem ; and the proportion of them 

 increases as it ascends. The substances at first produced are gum 

 and sugar, which are the simplest in their chemical nature of all 

 organic compounds ; being made up of oxygen and hydrogen, in 

 the same proportion as water contains, with the addition of car- 

 bon. Being nearer inorganic bodies in their composition, and in 

 the tendency of the latter to the crystalline form, they are also 

 nearer in properties ; for they may be preserved for years in a 

 dry state, without any impairment of their characters ; since 

 their tendency to spontaneous decomposition is not greater than 

 that of many mineral substances. 



318. The crude sap, immediately that it has been absorbed, 

 b gins to mix with the matter which has been stored up from 

 the previous year, in the tubes and vessels through which it rises; 

 and in proportion as it ascends the stem, it dissolves more and 

 more of this, so as gradually to present in taste, odour, &c., the 

 peculiar characters of the plant itself. One object of this admix- 

 ture has been already stated (. 119) ; but some other is not 

 improbably answered by it. 



