37° C., is determined. The deviations are noted at certain intervals. If there is no change in the deviation, then we conclude that no decomposition has taken place. Should there be an alteration in the rotation after some time, then we must infer a fermentative decomposition, such as has been demonstrated by special experiments with ferment solutions.
We shall now give a description of the preparation of the peptone.
Preparation of Peptones for use in the Optical Method.
Organs are first deprived of their blood, in exactly the same way as has been described on p. 164. They can then be subjected directly to hydrolysis, after the pieces of tissue have been dried, as much as possible, between filter papers. If it is desired to collect larger quantities of the same tissue, then the tissue, freed from blood, is boiled for ten minutes in water, and is subsequently preserved in sterilized water with chloroform and toluol. It is, of course, not necessary, in this case, to boil the organ to such an extent, as to deprive it of all substances reacting with ninhydrin. Boiling is merely resorted to here, in order to destroy any cell ferments that may be present; otherwise autolysis may manifest itself. As soon as enough of the organ has been collected,
