THE FERMENTS. Ill 



await their final solution. That the life of the cell is not insepar- 

 ably connected with the activity of its ferments has been well 

 shown by Btichner : If common yeast is placed in a solution of 

 cane-sugar, this is inverted to glucose and Ia3vulose by the contained 

 invertin ; at the same time the cell causes the further destruction 

 of these sugars with the formation of alcohol and carbon dioxide. 

 The fact that this latter process can be prevented by means of 

 chloroform, which is a notable protoplasmic poison, while the inver- 

 sion proceeds as before, was formerly interpreted as evidence of a 

 special vital activity on the part of the cell. Buchner, however, 

 has demonstrated conclusively that there is no true cause for this 

 assumption. For on crushing the yeast-cells completely he succeeded 

 in obtaining a fluid which could bring about the further destruction 

 of glucose and Isevulose exactly as in the case of the living cell. 

 He could show that this action is referable to an intracellular fer- 

 ment which is termed zymase. By similar methods a large number 

 of intracellular ferments have been discovered in the animal body 

 (see below). 



The ferments proper must be sharply distinguished from the so- 

 called ferment-organisms, or organized ferments, which occur widely 

 distributed in nature and comprise the important groups of bacteria, 

 blastomycetes, and certain moulds. These are living beings them- 

 selves, and not, as the ferments proper, products of life. They 

 contain ferments, and manifest their special activity, in a great 

 measure, through their ferments ; but they are not ferments them- 

 selves, although they are often so called. In contradistinction to ' 

 these organized ferments, the ferments proper are termed non- 

 organized ferments, or enzymes. They are specific products of the 

 activity of cells, and occur widely distributed in the animal and 

 vegetable world. 



For the maintenance of life, in the case of the higher plants at 

 least, the organized ferments are of prime importance ; for, as has 

 been seen, it is through these low forms of life that the higher plants 

 are furnished their nitrogen in a form which they can subsequently 

 utilize. In their absence from the soil, vegetable life, such as we see 

 it, could probably not exist. In the gastro-intestinal tract of all 

 animals which have been examined in this direction innumerable 

 bacteria are also found, and it was long thought that their presence 

 here served a very definite purpose, and that animal life could not 

 go on in their absence. This view, however, has proved erroneous, 

 as Nuttall and Thierfelder conclusively demonstrated. They showed 

 that when a young guinea-pig, for example, is removed from the 

 mother animal by Csesarean section under strict aseptic precautions, 

 and is subsequently fed with sterile food and is furnished with sterile 

 air, it will grow as well as a control-animal. While the presence of 

 bacteria in the animal body is therefore not essential for the main- 

 tenance of life, and while it is very questionable, indeed, whether 

 their presence in the alimentary canal serves any useful purpose at 



