14 BIOLOGY. [Book ii. 



re may employ this word in speaking of blind orga nic jSnal ity) 

 —it was destined to be burned by the beet-root itself during the 

 econd year of vegetation, when florescence and fructification are 

 leveloping themselves. 



However this may be, the nutritive substances, when suf- 

 iciently elaborated, are assimilated ; that is to say, their molecules 

 Qtercalate themselves between the organic molecules already 

 ormed, either to replace those which have been destroyed, or to 

 iring about the enlargement, of the cell ; others spontaneoply 

 rganize themselves in the blastemas. 



We may form some probable conjectures as to the special office 

 f the various categories of organic substances. It is probable 

 hat the hydrates of carbon and the fatty bodies are especially 

 ransf ormed into cellular membranes, these membranes being prin- 

 Lpally constituted of cellulose, the molecule of which is almost 

 identical with that of starches, sugars, and fats. Thence come 

 Iso without doubt the vegetal acids, tannin, and the colouring 

 latters. 



The proteic Substances are probably employed in the formation 

 f internal azotized utricles included in the cells, and of the 

 ellular protoplasm and the chlorophyllian particles. 



They also furnish, but by incomplete oxydation, by degradation, 

 sparagin, of which we have spoken, and without doubt the 

 egetal alkaloids (quinine, morphine, strychnine, &c.), quaternary 

 ut not proteic substances, and of which the molecule, very 

 omplex, very rich in carbon, and tolerably rich in hydrogen, 

 ontains also a notable proportion of oxygen and very little 

 zote. 



2. Inorganic Substances. 



Besides atmospheric gases, a number of mineral substances are 

 Qtroduced into the plant through the roots. The principar are 

 Ikaline and terreous bases : potash, soda, ammonia, magnesia, 

 ime, generally salified by sulphuric, azotic, phosphoric, silicious' 

 nd carbonic acids. Many of these substances do not contribute 



