Note 82 — Chapter IV

The modification of Soyka’s method of making attenuations of bacteria is that of Günther (Bakteriologie, 1898, p. 204), and is carried out as follows:—On the inner surface of the cover of a sterile Petri dish (which is to be used for making the plate culture), place four drops of sterile broth, or sterile water; inoculate the first drop, by means of a platinum needle, with the material to be examined; heat the needle in the flame, dip it into the first drop, and, with the liquid adhering, inoculate the second drop. Proceed in this way, each time heating the needle, to the fourth drop. From this fourth drop a tube of nutrient gelatin is inoculated, and poured on to the plate. The cover is then put on, and the plate put into the incubator. The drops on the cover do not in any way contaminate the culture.