Studies Upon the Filterable and Non-Filterable State in the Tunnicliff Coccus of Measles

Abstract

This communication reports the results of tests upon the differences in filtrability of the Tunnicliff coccus of measles under in vivo and in vitro growth conditions. The question whether microorganisms ordinarily regarded as non-filtrable can become filtrable and vice versa, under special conditions of growth, is of more than academic interest. Kendall, 1 with the use of his “K” medium, claims that it is relatively easy to cause non-filtrable organisms to become filtrable and filtrable to become microscopically visible and non-filtrable.

Different environmental conditions cause some microorganisms to undergo rather marked changes in size and shape of the individual cell. Particularly is this true for certain parasitic varieties capable of cultivation in vitro, where they are distinctly larger and often differently shaped than they are in vivo. Adaptation to the artificial environment is the accepted explanation for the morphological variation. The reaction of the culture medium, quality of nutritives, absence of the living host influence and the osmotic pressure are undoubtedly responsible for this in vitro metamorphosis.

Experiments. Full-grown, healthy guinea pigs were intracardially injected with 1 cc. quantities of a heavy saline suspension from a 24-hour blood-agar growth of pure cultures of the Tunnicliff coccus of measles. The cultures used for animal inoculation were isolated in 1926 by Duval and Hibbard 2 directly from the blood of human measles upon a modified Noguchi plasma medium. The morphology was that of a Gram positive diplococcus corresponding in size to the ordinary pneumococcus.