presence has been demonstrated in animals and plants inside the most varied kinds of cells. In plants they are not always found in an active state. In seeds, for instance, they appear only when these are beginning to germinate. In the same way they are absent, as Iwanow has shown at my Institute, when plants are resting during the winter. In the fœtus their presence can be demonstrated fairly early. They can be detected, for instance, in a chicken on the seventh day of development, while in embryos of swine active peptolytic ferments appear on about the fortieth day.
The demonstration of the peptolytic ferments may be performed in various ways. One way is to treat them in the manner adopted by Edward Buchner, namely, to entirely destroy the cells of certain tissues or even single cells by trituration with quartz sand, so as to squeeze out the internal fluid of the cells. This fluid is afterwards mixed with kieselguhr, which readily absorbs moisture from the cell fragments, and produces a compressible plastic mass. The absorbed juice is then extracted out of the latter under pressure—up to 300 atmospheres—and filtered through a filter candle. We get a clear juice, which contains many components of the cells; the original structure of these having, of course, disappeared. In a juice obtained in this manner the presence of various ferment activities can be demonstrated, and it may be
