ORGANISED AND UNORGANISED FERMENTS. 507 



(a.) Sugar-forming or diastatic ferment occurs in saliva (p. 294), pancreatic juice 

 (p. 340), intestinal juice (p. 335), bile (p. 366), blood (p. 36), chyle (p. 410), 

 liver (p. 351), in human milk (p. 465). Invertin in intestinal juice (p. 370). 

 (Cl. Bernard.) 



Almost all dead tissues, organic fluids, and even proteicls, although only to a 

 slight degree, may act diastatically. Diastatic ferments are very generally distri- 

 buted in the vegetable kingdom. 



(b.) Proteolytic or Ferments which act upon proteids. Pepsin in gastric juice 

 and in muscle (p. 332), in vetches, myxomycetes (Krukenberg), trypsin in the 

 pancreatic juice (p. 341 ) , and a similar ferment in the intestinal juice (p. 370). 



(c.) Fat-decomposing in pancreatic juice (p. 343) in the stomach (p. 335). 



(d.) Milk-coagulating in the stomach (p. 335), pancreatic juice (p. 344), and 

 perhaps also in the intestinal juice (?) W. Roberts. 



[The importance of fermentative processes has already been referred to in detail 

 under " Digestion." Ferments are bodies which excite chemical changes in other 

 matter with which they are brought into contact. They are divided into two 

 classes : 



(1.) Unorganised, soluble or non-living. 

 (2.) Organised, or living. 



( 1 . ) The Unorganised ferments are those mentioned in the above table. They 

 seem to be nitrogenous bodies, although their exact composition is unknown, and 

 it is doubtful if they have ever been obtained perfectly pure. They are 

 produced within the body, in many secretions, by the vital activity of the 

 protoplasm of cells. They are termed soluble because they are soluble iu water, 

 glycerine, and some other substances (p. 295), while they can be precipitated by 

 alcohol and some other reagents. They do not multiply during their activity, nor 

 is their activity prevented by a certain proportion of salicylic acid. They are 

 not affected by oxygen subjected to the compression of many atmospheres 

 (P. Bert). They are non-living. Their other properties are referred to above]. 



[(2.) The Organised or living ferments are represented by yeast (p. 474). 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 (p. 298), 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 acid, or chloroform, all of 

 which destroy its activity, it cannot produce the alcoholic fermentation. 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 compression 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. 



All purely physiological processes in the body, except some in the intestinal 

 canal, depend upon unorganised ferments]. 



10. Haemoglobin, the colouring matter of blood, which, in addition to 

 C,H,0,N, andS, contains iron, may be taken with the albuminoids (p. 23). 



