246 MICRO-ORGANISMS AND FERMENTATION. 



position of the sugar molecule and the special conditions under 

 which it took place still awaited solution. 



Meanwhile, in the last decade of the nineteenth century,, 

 new views regarding the fermentative forces were gaining 

 ground, when it proved possible to separate the exciter of 

 fermentation in certain cases (diastase from malt, pepsin from 

 gastric juice). The characteristic effect of these ferments was 

 that minute quantities were able to split up large amounts of 

 the given material, and that they completely lost this power 

 when subjected to heat. The name enzyme was applied to> 

 the substances isolated from the living cells of the barley corn, 

 the mucous membrane of the stomach, etc., and gradually a 

 large number of these ferments were distinguished, amongst 

 them some of great technical importance. 



The thought naturally suggests itself that it must be 

 possible to find such an enzyme amongst the many elements 

 of which the living yeast cell is constituted which would be 

 capable of splitting up sugar. As early as 1858 we find & 

 suggestion of this kind put forward by Traube that " the 

 chemical processes going on in living organisms originate 

 mainly in the circumstance that protein substances are liable 

 to undergo decomposition in the presence of water, and that 

 under the peculiar conditions actually obtaining they are also- 

 apt to give rise to peculiar ferments." A direct outcome of 

 this view was Miquel's discovery in 1890 that the bacterium 

 causing the ammoniacal fermentation of urine contained an 

 enzyme which can bring about this fermentation on its own 

 account. 



In 1894 Emil Fischer, by purely chemical research, resulting 

 in his celebrated work on the synthesis of the sugars, on the 

 use of phenyl-hydrazin, and the osazone-reaction, diverted the 

 current views on fermentation phenomena into new channels. 

 His researches led him to explain the behaviour of the yeast 

 cell towards the particular sugar of the nutritive liquid in the 

 same way as that of the enzymes (invertase, emulsin), so that 

 the chemical activity of the living cell does not differ from 

 the action of chemical ferments. According to Fischer, fer- 

 mentation of polysaccharides is always preceded by hydrolysis 

 of the sugar. But there exists an exact relation between the 



