A new culture medium for Protozoa

Abstract

Although there are many media extant for cultivating try-panosomes in test tubes, a satisfactory medium for culture on a slide under a cover glass has hitherto not been described, in spite of the fact that only by the slide method is it possible to study the sequence of changes with the greatest accuracy. The method here outlined makes possible the continued study of the life history of the organism either in prepared culture medium or in inoculated tissue.

As a culture medium the plasma of the host is employed and this is either inoculated with the trypanosomes themselves or used as a medium for the growth in vitro of various infected tissues of the host. I have used the plasma of the rat in studying the development of Trypanosoma brucei and have been able to keep the trypanosomes in a normal condition for an indefinite period whereas by the use of Ringer's fluid or blood bouillon the organisms die after a few days.

The plasma was obtained by the method of Harrison, 1 Burrows, 2 and Walton, 3 the latter making adaptations for mammalian plasma. In brief, the blood from the infected rat was taken and put into a small drop of plasma on a cover glass and then this was further diluted with plasma in order to reduce the number of blood corpuscles in the hanging drop which was taken from this. The cover glass with hanging drop was either placed on a depression slide or on a regular slide for study with dark field illumination. In essentially the same way pieces of tissue were placed in plasma under a cover glass and sealed. Precautions to secure aseptic conditions were taken.

This method keeps trypanosomes living, growing and dividing, and thus many of the stages described by various authors either in the host itself or in the transmitter have been studied in vitro.