Fusiform Bacilli. Isolation and Cultivation

Abstract

methods were found unsatisfactory. The possibility of success depends on an abundance of bacilli in the original material or the examination of smears from colonies till one might chance on a fusiform colony. The use of surface growths was not seriously considered, as we were endeavoring to dispense with the use of pyrogallic acid. Shake cultures in capillary tubes were then made so that the character of the colonies could be studied under the microscope. This was also found unsatisfactory. The cultivation in agar contained between two layers of glass was then tried. For this purpose the two halves of the petri dish were sterilized so that the bottom was placed in the inverted cover. The inoculated ascitic agar was poured into the cover and the bottom of the dish was laid on top of the agar while it was still fluid. A very few threaded colonies were noted and fishing from these gave fusiform bacilli. This gave us the basis for future work. The original material is suspended in about 5 to 7 c.c. of ascitic fluid or horse serum, and successive dilutions made in a series of tubes containing the same amount. In making the dilutions a pipette is used carrying over about 0.1 to 0.2 c.c. to make the dilutions gradual. About 15 c.c. of fluid agar is then poured into the tubes and the mixture poured in the manner already described (Fig. 1). During incubation the plates should be covered with paper to limit air contamination of the rim of exposed agar or the