MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 729 



Infection by inoculation is the most common method of introducing 

 the disease; but infection by inhalation evidently occurs in some cases. 

 It seems probable that some special stage of development for the Acti- 

 nomyces is necessary either within the diseased animal body or upon 

 some plants, in order that it may be able to infect animal bodies, for 

 direct inoculation by pus has usually given negative results. Inocula- 

 tion by bits of diseased tissue occasionally gives positive results. 



It is evidently not a producer of active toxins for the disease dis- 

 turbances are apparently due to harmful growth in the tissues and to 

 secondary infection. 



Suppuration is one of the conspicuous features as is also the develop- 

 ment of much new granulation tissue which tends to degenerate at the 

 center. Soft organs affected by this parasite show a tendency to multi- 

 ple abscesses. 



FtG. IS4- — Actinomycosis. Actinomyces bovis. Preparation from a pure culture. 

 Xiooo. {After Williams.) 



Actinomyces bovis grows rapidly on a variety of laboratory media. On glycerin 

 gaar the colonies develop into transparent drop-like bodies in four or five days at 

 73°. Old colonies become white or yellowish with a powdery surface. The cultural 

 and other peculiarities vary much and according to .the variety under observation. 

 Some varieties appear distinctly aerobic and others anaerobic. As a rule it liquefies 

 gelatin growing in spherical masses which settle to the bottom of the liquid. Fila- 

 ments fippeaj- in artificial growth which are very long and slender, and about 6/i« 



