154 I'LANT 8Tl'liIK.S 



hydrates, tlio nitrogL^i, Kulphur, aud other necessary 

 additional eh'inciits l)ei)ig ol)taiiied from soil snljstancos 

 dissolved in the water which is aljsorltod and conveyed 

 to the leaves. 



li:!. Transpiration. — The water which is absorbed by the 

 roots and passes to the leaves is mnch more alnindant than 

 is needed in tlie process of pliotosynthesis. It should l)e re- 

 membered that the water is not only used as a raw material 

 for food manufacture, but also acts as a solvent of the soil 

 materiids a.nd carries them into the plant. 'I'hc "water in 

 excess of the small annjunt used iu f(i(id manufacture is 

 given off from the plant in the form of water va])or, the 

 process being already referred to as / rtnisjiird/iuii. (sim; g;.'li). 



114. Digestion. — Ciarliohydratcs and proteids may l)e re- 

 garded as prominent types of plant f<.)od wliicli green 

 plants are able to manufa(-ture. Tliese foods are trans- 

 ported through the plant to regions wlicre work is going on, 

 and if there is a greater supply of food tliaii is needed for 

 the working regiojis, the excess is stored up iu some })art 

 of the plant. As a rule, green plants are aide to manufac- 

 ture much more food than they use, and it is upxm this ex- 

 cess that other plants and animals live. In tlie transfer of 

 foods tlirougli the plant certain changes ai-e often neces- 

 sary. Vov exaujple, starch is insoluljle, and bem^e cannot 

 be carried al)out in solution. It is necessary to transform 

 it into sugar, wluch is soluble. These clumges, nu^de to 

 facilita'_e the transfer of foods, represent ilii/i'sfimi. 



115. Assimilation. — When fo(]d in some form lias i-eached 

 a wofkiiig regii)n, it is organized into tlie living sul)stance 

 of the jilant, known as protoplasm, and tlie pr(ito]ila,sni 

 builds tlie jdant structure. This process of oi'ganizing tlie 

 food into the living su1)stance is known as (tssimlhil ion.. 



lie. Respiration. — The formation of foods, tlieir diges- 

 tion and assimilation arc all prejiaratory to I he ])rocess of 

 respiration, which may be I'alleil the use of assimilated 

 food. 'Idle whole working |io\\-('r of the plant dc|n'nds 



