FIBRINE. 85 



sence of albuminous matters, which appear to supply the necessary 

 material for their growth. They decompose these substances therefore 

 by assimilating their ingredients in the process of vegetable nutrition, 

 and the putrefactive gases are the final result of the changes thus taking 

 place, just as alcohol and carbonic acid are produced in the fermenta- 

 tion of saccharine liquids. 



Fermentation and putrefaction, accordingly, are analogous processes, 

 in which certain materials are decomposed under the influence of micro- 

 scopic vegetation. The former takes place in saccharine fluids, the 

 latter in those containing albuminous matter; since the yeast-plant 

 requires for its growth a preponderance of non-nitrogenized hydrocar- 

 bonaceous matter, while bacterium cells are nourished mainly by the 

 absorption of nitrogenous substances. 



The following table shows the proportion of albuminous matter, 

 according to Payen, in different substances used as food : 



QUANTITY OF ALBUMINOUS MATTER IN 100 PARTS IN 



Beef flesh . . . 19.50 Wheat grains . . 18.03 



Fowl's eggs . . 12.35 Rye .... 12.50 



Mackerel . . . 24.31 Oats .... 14.39 



Salmon . . . 13.58 Indian corn . . 12.50 



Oysters . . . 14.01 Rice .... 7.55 



Beans (dry) . . 24.40 Potatoes . . . 2.50 



Peas " . . . 23.80 Sweet potatoes . . 1.50 



The first formation of albuminous matter takes place in vegetables, 

 subsequent to the production of the non-nitrogenous organic substances, 

 starch and glucose, by the union of these last with nitrogen derived 

 from the inorganic salts. Green plants, which have the power of gene- 

 rating the carbohydrates from carbonic acid and water, if supplied with 

 moisture containing nitrates or ammonium salts in solution, are known 

 to grow vigorously and increase many fold their contents of albuminous 

 matter. 1 These salts must therefore have supplied the nitrogen requisite 

 for the formation of the nitrogenous substances. The sulphur, which 

 also enters into the composition of these substances, is derived by the 

 plants from a reduction of the soluble sulphates contained in the soil. 



Notwithstanding the very marked and important peculiarities which 

 distinguish the albuminous matters as a group, there are many of these 

 substances which differ from each other by a variety of secondary char- 

 acters. It is possible that some of those now designated by specific 

 names may really be mixtures of two or more distinct substances ; but 

 the classification at present in use expresses the distinguishing marks 

 of the more important varieties, so far as they are yet known. 



Fibrine. 



Fibrine is found in the plasma of the blood, where it exists in the 

 proportion, on the average, of three parts per thousand. It is also 



1 Mayer, Lehrbuch der Agrikultur-Chemie, Band i. pp. 145, 150. 



