FERMENTATION. 129 



dextrose, lose their power of transforming levulose at a still 

 earlier period. 



This enzyme function, although so intimately associated 

 with the vital activity of protoplasm and so usually possessed 

 by cells, is considered by Hueppe to be a secondarily derived 

 function of the protoplasm, and to be reUlly a modification 

 or development of the primary power of digestion possessed by 

 all protoplasm independent of the action of enzymes, only 

 to be met with when the conditions for the growth of the 

 organism and the development of its functions are most per- 

 fectly combined. It is, as Cartwright Wood says, a function 

 developed in such a high degree, that it may actually be 

 temporarily separated from the protoplasm which develops it. 

 It must be looked upon as something separate, and as some- 

 thing that can act, under favourable circumstances, apart 

 from protoplasm, economizing the energy of the proto- 

 plasm, and utilizing the most suitable products for the nutri- 

 tion of the organism and for the manifestation of its special 

 functions. Under less favourable conditions, where the pro- 

 toplasm has to struggle for existence, as it were, this enzyme 

 function is withdrawn ; and although the protoplasm can 

 still exert its characteristic powers of digestion and of forma- 

 tion of special products, these processes take place within 

 the cell, they are of a less specialized nature, and are, in fact, 

 the primary and inherent functions of the cell protoplasm, 

 which are capable of doing their work within the protoplasm, 

 but are not so highly differentiated that they can act exter- 

 nally to it. The primary function is, then, not separable 

 from the protoplasm. This formation of enzymes is of special 

 interest in relation to the processes of disease ; for it is found 

 that, by modifying the conditions under which an organism 

 grows, or by varying its food, special ferments come into 

 operation. For instance, Lauder Brunton and M'Fadyean, 

 experimenting with a certain organism, found that if it were 

 grown on peptonized beef jelly, it would give_ rise to an 

 enzyme which was capable of liquefying the gelatine. If this 

 organism were now introduced into a solution of starch, it 

 would continue to grow, but it could give rise to no diastatic 

 ferment — i.e., it was incapable of transforming, except within 

 its own protoplasm, the starch material into sugar, or into 

 material that it could utilize for its own nutrition. If, how- 

 ever, successive generations of this same organism were cul- 



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