Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/238

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STANDARDIZATION OF PEPTONES
213

from the other, as decomposition begins, and manifests itself for a certainty, only after about six hours. Readings should not be followed up for more than thirty-six to thirty-eight hours.

Great progress would be made, if the reading of angles of rotation could be taken by means of some kind of automatic device. Objective values could be obtained, and we should be in a position to follow

Fig. 11.

up details which, during the long intervals between readings, at present escape observation. Experiments in this direction, with the collaboration of Dr. Wildermuth, are in progress.

To obviate the cooling of the polariscopic tubes, during polarization, tubes have been constructed with water jackets (fig. 11). Lately, an electric heating apparatus[1] has been added to the polariscope itself.


  1. Emil Abderhalden: "Ueber eine mit Polarisations-apparat kombinierte elektrisch heizbare Vorrichtung zur Ablesung und Beobachtung des Drehungsvermögens bei konstanter Temperatur. Zeitschr. f. physiol. Chem., 84, 300 (1913).