270 ACT1NOMYCOSIS. 



In the cultures at an early stage, numerous bacillary 

 forms may be present, but later the growth is chiefly com- 

 posed of filaments which show distinct branching (Fig. 

 69). Older filaments may become broken up into "cocci." 

 True clubs are not formed in cultures, though slight 

 bulbous thickenings may be seen at the end of some of 

 the filaments. 



Experimental Inoculation. Some observers (e.g., Bos- 

 trom) have obtained negative results by inoculation on 

 animals, but Israel and Wolff succeeded in the case of 

 guinea-pigs and rabbits. Intraperitoneal injection of the 

 parasite in the bacillary or filamentous form was followed 

 in a month by the production of nodules in the peritoneum 

 from the size of a pea to that of a plum. The nodules were 

 composed of granulation tissue, vascular on the surface, 

 and containing fatty pus in which colonies of typical 

 structure lay. These colonies showed clubs, though clubs 

 were not present in the culture injected. The disease can 

 also be reproduced by direct inoculation from an animal 

 affected. 



Methods of Examination and Diagnosis. As actino- 

 mycosis cannot be diagnosed with certainty apart from the 

 discovery of the parasite, a careful examination of the 

 pus in obscure cases of suppuration should always be 

 undertaken. As already stated, the colonies can be recog- 

 nised with the naked eye, especially when some of the pus 

 is spread out on a piece of glass. If one of these is 

 washed in salt solution and examined unstained, the clubs, 

 if present, are at once seen on microscopic examination. 

 Or the colony may be stained with a simple reagent such 

 as picrocarmine, and mounted in glycerine or Farrants' 

 solution. To study the filaments, a colony should be 

 broken down on a cover -glass, dried, and stained with a 

 simple solution of any of the basic aniline dyes, such as 

 gentian-violet, though better results are obtained by carbol- 

 thionin-blue, or by carbol-fuchsin diluted with five parts 

 of water. If the specimen be over- stained, it may be 

 decolorised by weak acetic acid. Cover-glass preparations 



