i6a PATHOGENIC BACTERIA. The animal should be tacked to a board if small, or tied, by cords fastened to the legs, to the corners of a table if large, and should be dissected with sterile knives and scissors. When a culture is to be made from the interior of an organ—say the spleen—it should be incised deeply with a sterile knife and the culture made from its centre. Fragments intended for subsequent microscopical ex- amination should be cut very small (cubes of i c.cm.), placed in absolute alcohol for a few hours, then trans- ferred to weaker alcohol, 80-90 per cent, for preserva- tion. The technique of imbedding and staining the tis- sues can be found in almost any reliable text-book on pathology or on the special subject of microscopical technique.