380 UNORGANISED FERMENTS. 



[The unorganised ferments present in the body, and their actions ( W. Roberts) 



[(2) The Organised or living ferments are represented by yeast ( 235). Other living 

 ferments belonging to the schizomycetes, occurring in the intestinal canal, are referred to in 

 $ 184. Yeast causes fermentation by splitting up sugar into C0 2 and alcohol ( 156), but this 

 result only occurs so long as the yeast is living. Hence, its activity is coupled with the 

 vitality of the cells of the yeast. If yeast be boiled, or if it be mixed with carbolic or salicylic 

 arid, or chloroform, all of which destroy its activity, it cannot produce the alcoholic fermenta- 

 tion. As yet no one has succeeded in extracting from yeast a substance which will excite the 

 alcoholic fermentation. All the organised ferments grow and multiply during their activity at 

 the expense of the substances in which they occur. Thus the alcoholic fermentation depends 

 upon the " life " of the yeast. They are said to be killed by oxygen subjected to the compres- 

 sion of many atmospheres {P. Bert). But it is important to note that Hoppe-Seyler has 

 extracted from dead yeast (killed by ether) an unorganised ferment which can change cane- 

 sugar into grape-sugar.] 



10. Haemoglobin, the colouring matter of blood, which, in addition to C, H, 0, N, and S, 

 contains iron, may be taken with the albuminoids ( 11). [Haemocyanin ( 32).] 



(3) Glucosides containing Nitrogen. 



In addition to chondrin, the following glucosides containing nitrogen, when subjected to 

 hydrolytic processes, may combine with water, and form sugar and other substances: 



Cerebrin ( 322) = C B7 H 110 N 2 O25 (Geoghcgan). [Parcus has shown that cerebrin as originally 

 prepared by W. Muller is a mixture of three bodies, viz., cerebrin, homocerebrin, and 

 encephalin. ] 



Protagon C 66 '29, H 10'69, N 2*39, PI '068, per cent. occurs in nerves, and contains 

 phosphorus ( 322). 



Chitin, 2(C 15 H 2fl N0 10 ), is a glucoside containing nitrogen, and occurs in the cutaneous 

 coverings of arthropoda, and also in their intestine and tracheae ; it is soluble in concentrated 

 acids, e.g., hydrochloric or nitric acid, but insoluble in other reagents. According to Sandwick, 

 chitin is an amin-derivative of a carbohydrate with the general formula n(C 12 H 20 O 10 ). The 



