Quantitative experiments were used to test the effect of supplements to a basic medium of the residue fraction remaining after ultrafiltration of horse serum. This study was carried out on washed cell suspensions of clone 929 strain L cells, originally obtained from a strain C3H mouse. These cultures were planted in T-15 flasks on glass substrate, and changes in population levels were determined by enumeration of the nuclei at 7-, 10-, 13-, 14-, and 21-day intervals.

The unsupplemented fraction of the horse serum was incapable of maintaining the inoculum level beyond 7 days.

This residue medium, supplemented with the amino acids, amides, and amine of horse serum was less effective in maintaining population levels.

The further addition of niacin, p-aminobenzoic acid, niacinamide, pyridoxine·HCl, thiamin·HCl, d-Ca pantothenate, i-inositol, choline chloride, riboflavin, ascorbic acid, glutathione, cysteine·HCl, biotin, folic acid, vitamin A, vitamin D (calciferol), Tween 80, menadione, vitamin E, and ATP, as contained in mixture 199 of Morgan, Morton, and Parker, gave population levels superior to those obtained by use of unfractionated horse serum. Under the experimental conditions used, addition of the other components of mixture 199 to this medium gave no added increase in proliferation and, in fact, indicated a possible inhibitory action.


This article represents in part a thesis (by M. C. F.) presented to the faculty of The George Washington University in partial fulfilment of the requirements for the degree of Master of Science.

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