AMYLASE IN THE LIVING CELL 123 



with a little thymol in order to inhibit vital phenomena, and 

 adding the mixture to a further quantity of starch gelatine, 

 when saccharification will continue, showing that the change 

 is due to an enzyme secreted by the organism which is capable 

 of acting whether the organism be alive or not. 



Besides numerous bacteria a certain number of moulds are 

 also capable of secreting amylase, e.g., Aspergillus niger ; this 

 can readily be shown by making a streak culture (Fig. 5 6.) of 

 this organism in a tube of starch gelatine. After some days, 

 when a vigorous growth of the mould has taken place, the 

 gelatine may be melted, dissolved in warm water, and filtered 

 from the mould and the filtrate tested with Fehling's solution 

 for the presence of maltose. 



All the foregoing experiments necessitate care in manipula- 

 tion in order to prevent infection by extraneous organisms, 

 but with a little practice in bacteriological technique they are 

 not difficult to carry out and are highly instructive. The 

 secretion of an enzyme, such as amylase, is analogous to the 

 secretion of toxins by pathogenic organisms, and the chemical 

 problems involved in all these cases are of a similar nature. It 

 will be shown later that certain organisms, e.g., Aspergillus 

 niger, are capable of secreting enzymes suitable to the conditions 

 of their environment. Thus, e.g., Aspergillus niger, is capable, 

 not only of saccharifying starch, but also of inverting cane 

 sugar and of splitting up fats ; in fact, it has been shown by 

 Delepine that this organism can derive sus enance from 

 almost every conceivable organic medium. Similarly, a yeast 

 cell can bring about quite a number of different chemical 

 changes. Organisms of simpler structure and function, such 

 as bacteria, are more limited in their range of activity, but there 

 is no doubt that they too are capable of bringing about a 

 variety of changes according to their differing environments. 

 A possible explanation suggests itself here of the difference in 

 pathogenic effect, which is observed when the same organism 

 is cultivated under differing conditions. 



