106 THE FERMENTS. 



the other hand, that are capable of effecting the various hydrations 

 and oxidations which take place in the tissues of the body, we have 

 not made mention. As a matter of fact, it must be admitted that 

 with very few exceptions we have no knowledge as yet of the 

 existence of such ferments. I say, "with very few exceptions," for 

 there are a few ferments which have been obtained from the tissues,, 

 and which are certainly not identical with the known digestive 

 ferments. For the sake of convenience, I shall, for the present. 

 speak of these as : 



8. The Tissue-ferments. Members belonging to this group have 

 been found in the liver, the kidneys, the spleen, the adrenal glands, 

 the muscles, etc., and have long been regarded as identical with t In- 

 digestive ferments. Some of them, no doubt, are closely related to 

 these, and, like them, capable of bringing about hydrolytic dec* im- 

 position of albumins and carbohydrates. Others, however, are dis- 

 tinctly different in being essentially oxidizing ferments. From recent 

 studies of these oxidizing ferments it appears that different varieties 

 exist. One of them, the so-called aldehydase of the liver, has been 

 more carefully studied, and will be considered in greater detail later. 



Of special interest is a ferment which has likewise been obtained 

 from the liver, and which is capable of transforming the closely 

 combined nitrogen of albumins into amido-nitrogen, and of splitting 

 this off in the form of ammonia. 



From what has been said, it is clear that our knowledge of the 

 agencies which are at the disposal of the animal body in order to 

 effect those chemical changes that are necessary for the maintenance 

 of life is very imperfect. That ferments bring about transforma- 

 tion of the native food-stuffs into chemical bodies which can be 

 assimilated, and subsequently rebuilt into tissues, we know. That 

 other ferments exist which can cause destruction of the organized 

 tissues, with the formation of substances that can be readily removed 

 from the body, is extremely probable. But whether all the vital 

 manifestations of the animal tissues can be reduced to the activity 

 of ferments, we do not know. It has been pointed out that living 

 cells possess the power of causing chemical changes which differ 

 from those that are effected by their contained ferments, and the 

 question naturally suggests itself, To what extent are the kata- 

 bolic phenomena which we observe in the animal body referable to 

 pure protoplasmic activity, as compared to the action of ferments ? 

 This question, however, we are not yet prepared to answer. \Ve 

 know that living protoplasm is capable of causing oxidation of non- 

 living matter, but we do not know in what manner this is brought 

 about. Possibly this power is referable to the presence in the cell 

 of ferments which may yet be isolated, and which may manifest 

 their activity, like that of the other ferments, even after the death 

 of the mother-cell ; but it is also possible that this power depends 

 upon the presence in the (M'll of combinations of atoms which cannot 



