ACTINOMYCOSIS. 439 



eggs, and succeeded, by inoculation in the peritoneal cavity, in 

 producing the disease in rabbits and guinea-pigs, in the form of 

 tumours of the peritoneum. Sauvageau and Radais consider that 

 actinomyces should not be included with bacteria, and have suggested 

 the name Oospora hovis. 



Preparation akd Examination of Tissues. 



In order to examine the microscopical appearances, the tissues should 

 be hardened in absolute alcohol and embedded in celloidin. The sections, 

 when stained, are to be dehydrated as a rule iu strong spirit instead of 

 absolute alcohol, as the latter dissolves the celloidin. If the sections are 

 very friable, they can be cleared with clove-oil on the slide. By these 

 means the little fungus tufts, which have a great tendency to fall out of 

 the sections, may be preserved in situ after passing through the various 

 staining processes. To cut the sections, we can use either Jung's micro- 

 tome, cutting in alcohol, or the freezing microtome. In the latter case, 

 after the celloidin has hardened, it is necessary to shave off all that 

 surrounds the piece of tissue. It is placed in water until it sinks, and 

 then transferred to gum, and frozen and cut in the ordinary way. 



Staining Methods. 



There are several methods by which the organism can be stained in 

 the tissues, but it is best to eniploy for this purpose Gram's method and 

 modifications of Plaut's method. 



Gram's Method. — By Gram's method the clubs in the bovine disease 

 are distinctly stained, especially if the sections contain the fungus at a 

 suitable stage. Use freshly prepared staining solution. A few drops of 

 aniline-oil are placed in a test-tube, which is filled up with distilled 

 water, the mouth of the tube closed with the thumb, and the mixture 

 shaken up thoroughly. An emulsion forms, which is then filtered, until a 

 perfectly clear solution of aniline-water is obtained. To this is added, 

 drop by drop, an alcoholic solution of gentian-violet until precipitation 

 commences. About fifteen to twenty drops in a small capsule of aniline- 

 water will be sufficient. Sections are floated in this dye for about ten 

 minutes, then transferred to the iodine-potassic-iodide solution until they 

 turn brown like a tea-leaf. They are then decolorised in alcohol ; then 

 stained in a weak alcoholic solution of eosin, dehydrated in strong com- 

 mercial alcohol, cleared in clove-oil, and mounted in balsam. It will be 

 found that the clubs are stained blue, and that there is a central area, 

 which is, as a rule, tinged by the eosin. There are various modifications 

 of the method, and some of them are extremely successful in affording 

 not only a picture of the fungus, but also the structure of the surrounding 

 tissue. Very instructive results may be obtained by combining the 

 method of Gram with Ehrlich's histological stain. In this case, after 

 the section has been decolorised in alcohol, it is ready to be transferred 

 to logwood and treated as described below. 



Weigert's Method. — This also gives very beautiful results. The sections 



