DI ASTATIC FERMENTS. 343 



means sufficient information concerning them as to whether these changes are 

 always eflfected by ferments, or do not occasionally occur by other means, the great 

 importance of this category of ferments nevertheless lies in that they are known 

 in very many cases to re-invigorate the plastic substances. 



In this category, alone to be considered here, two chief kinds of ferments are 

 to be distinguished, namely, the diastatic ferments and the peptonising ferments. 

 The former convert various carbo-hydrates into glucoses, while the different proteid 

 substances are transformed by the latter into peptones. As a third subdivision may 

 be added the emulsifying ferments which act upon fats, and which will be spoken 

 of subsequently. 



The longest and best known diastatic ferment in plants is Diastase, produced 

 on the germination of the seeds of barley and other grasses : it may be extracted 

 from the seedling by water or glycerine, and is capable of transforming enormous 

 quantities of starch into glucose, especially at higher temperatures below 70° C. A 

 few drops of an extract obtained in this way added to a considerable quantity of 

 boiled solution of starch, transforms it completely into sugar in a few hours ; and 

 fresh starch-grains at the ordinary temperature (15-25° C.) are in a short time 

 corroded and finally dissolved entirely, as previously described. Since, now, in the 

 germination of all starchy seeds, tubers, bulbs, and other reservoirs of reserve- 

 materials, exactly the same alterations of the starch-grains take place, and the starch 

 disappears with the formation of sugar, it may be supposed a priori that in all these 

 numerous cases, diastase, or at any rate similar diastatic ferments, produce the effect 

 mentioned. And, as a matter of fact, Baranetzky has shown that in all cases where 

 he looked for the diastatic ferment in starchy seeds, tubers, stems, and even leaves, it 

 was to be found ; and even in organs which contain no starch but abound in sugar, 

 as in the Carrot (flaucus carotd) and Turnip {Brassica Rapa),' the same observer 

 found a diastatic ferment. In seeds containing starch, the ferment may appear before 

 the commencement of germination ; generally, however, it only appears when growth 

 begins. 



It was formerly the custom to distinguish, as Invertin, a substance produced 

 by the Yeast-plant, Bacteria, and Mould-fungi, which splits cane-sugar into dextrose 

 and levulose (two species of glucose which reduce cuprous oxide), which then 

 undergo further decompositions under the influence of these Fungi. That a similar 

 ferment occurs also in the wintering Beet-root, may be concluded from the fact that 

 the cane-sugar collected as a reserve-material in its tissues is transformed into glucose 

 in the following spring, when the flowering shoots are developed ; and a similar phe- 

 nomenon occurs on the development of the fruiting spikes of Indian corn, the 

 parenchyma of the stem of which previously contained large quantities of cane- 

 sugar. The inulin in the tubers and perennial root-stocks of the Compositse, more- 

 over, as I showed twenty years ago, is transformed into glucose when the shoots 

 begin to grow, whence we may conclude that here also a diastatic ferment resembling 

 invertin co-operates. 



The ferments appear to be always produced by the growing parts of the 

 seedlings and buds themselves, and to penetrate from these into the reservoirs of 

 reserve-materials, there to dissolve or make active the constructive materials. This 

 is particularly evident in the case of seeds containing endosperm. If the young 



