LIFE OF THE PLANT-CELL. 83 



them as albumen, fibrin, and casein, we must allow for the absorption 

 of sulphur and phosphorus, as well as salts of sulphuric and phosphoric 

 acids : through this the phenomena become much more complicated. 

 The reduction of the phosphates and sulphates to phosphoric and sul- 

 phuric acids, and the separation of the sulphur or phosphorus and the 

 oxygen, indicate complicated chemical processes, which are not, however, 

 performed without the presence of nitrogenous substances, and thus they 

 appear to be the simplest additions to the plant-cell next the formation 

 of protein. The notion of such changes is justified by Mulder's re- 

 searches upon the mother of vinegar (Mycoderma Pers.), which is 

 formed out of hydrated acetic acid and the albumen contained in the 

 vinegar. It is composed of cellulose and protein, which always exist in 

 the proportion of one equivalent of protein with four of cellulose.* A 

 similar accurate examination of the fermentation-cells would be of the 

 highest interest. 



The plant-cell takes up all substances that are in solution in water, 

 both mineral and vegetable poisons and tannin, which, by producing an 

 interruption of the chemical processes, are capable of destroying its life. 

 The cell in this view has no choice beyond the endosmotic power of the 

 various substances which are presented to it. \ On the other hand, every 

 fluid is unfit for the nutrition of the cell, which, on account of its specific 

 nature as alcohol, or its density as concentrated solutions of sugar and 

 gum:}:, renders endosmose impossible, should it even contain all the 

 elements necessary for the growth of the cell. 



In the last place we may observe, that in the changes which are 

 undergone in the cell of the plant there is no individual element, with 

 the exception of oxygen, which takes part alone in those chemical pro- 

 cesses. Nitrogen is taken in with water, but passes out again without 

 undergoing any change. Hence all calculations with regard to the 

 composition and metamorphoses of organic bodies, in which the pure 

 elements, and not their combinations, are supposed to play a part, must 

 be rejected as hypothetical. 



II. On the Assimilation of the absorbed Matters, and Secretion. 



33. The assimilated substances consist of carbon, hydrogen, oxy- 

 gen, and nitrogen (sometimes with sulphur and phosphorus) ; and these 

 are only assimilated from the definite combinations, carbonic acid, 

 water, and ammonia. As soon as these substances are conducted 

 into the interior of the cell, in the before-mentioned manner, che- 

 mical processes originate which first commence in the destruction 

 of the ammoniacal compounds and (perhaps as a result) the decom- 

 position of the water, and whose progress is distinguished by the 

 action of the assimilated nitrogenous matter (mucus) upon non- 

 nitrogenous substances. Thus are formed at the same time both 

 mucus and non-nitrogenous substances. 



* Liebig's Annalen, vol. xlvi. p. 207. 



f See the experiments of Saussure, Chemische Untersuchungen iiber die Vegeta- 

 tion, Leipzig, 1805, p. 228. 



\ De Saussure and Davy found that plants flourished on dilute solutions of gum and 

 sugar. 



Davy, Elements of Agriculture. 



