The yeast test as a quantitative measure of vitamine

Abstract

The details of this paper will be reported in full in another publication. The experiments reported covered the following points:

1. A comparison of yeast test results (Funk 1 technique) with the material used by Osborne and Mendel 2 in a feeding test with rats. The test was shown to merely approximate the results of the feeding test but when the dilution of the extracts were such that the content of one gram was present in 250 c.c. of water the agreement was much more exact. This result agrees with Funk's findings that the extract test must fall within the steep part of the curve of stimulation if it is to be used comparatively.

2. A report of the result of 284 determinations on varying dilutions of an extract of alfalfa meal which in its highest concentration contained the extract of 400 grams of meal in 1,000 c.c. of water. This shows that the curve of stimulation is a curve with a definite shape which rises steeply from the control point to an optimum and then gradually declines to the right of the optimum. It also shows that there is greater variability in the region to the right of the optimum in the individual determinations. These results indicate clearly that if vitamine B is a factor in the test it is only one of several and that critics of the test are right in saying that comparisons cannot be made between the extracts of equal weights of extracted material at the present itme.

3. A series of studies on other sources showing that dilution produces similar results to those in alfalfa extracts but that the optima and shape of the curve of stimulation differ with each substance tested though in general they show a steep rise, an optimum and in some cases a decline to the right of the optimum.