102 SPECIAL BACTERIOLOGY 



Pathogenesis. Affects the horse, rabbit, guinea-pig, ox, sheep, 

 dog, and mice. The disease can be produced in horses by rubbing 

 the acne scabs or a pure culture of the bacillus into the skin. 

 Guinea-pigs subjected to similar treatment succumb in twenty-four 

 hours. Subcutaneous injection in dogs and rabbits produces toxic 

 symptoms and death, but the bacilli do not spread over the body. 

 Mice and field-mice are not affected by rubbing, but by subcutaneous 

 inoculation, die in one to ten days with the formation of abscesses, 

 the bacilli being found in clusters in the organs. The natural disease 

 is transmitted by means of grooming utensils, harness, blankets, etc., 

 and is often localized in the regions covered by the saddle and the 

 girth. 



Tizzoni and Giovannini mention a case of acne contagiosa in man 

 which proved fatal in thirteen days, and from the blood and skin 

 they isolated a bacillus morphologically, and in cultures, resembling 

 the bacillus of mouse septica?mia, but it was not pathogenic for mice, 

 while it produced fatal results with rabbits and guinea-pigs, the 

 conditions being similar to those found in the man. They considered 

 this organism as only of secondary importance, and that the Staphylo- 

 coccus pyogenes was the cause of the acne. 



THE STREPTOTHRICES. 



The organisms belonging to this subdivision resemble in their 

 structure at one time the thread fungi, and at other times the 

 bacteria. Like the mould fungi, they form cylindrical threads out of 

 round cells which branch dichotomously, finally becoming visible to 

 the naked eye as irregular radiating thread masses or mycelia. Single 

 threads or fruit hyphae grow upwards out of the substance, free in the 

 air, and break up into chains of round germ cells (spores or conidia), 

 which detaching from the plant are carried by the air, and the 

 preservation of the species is thus assured. 



STREPTOTHRIX ACTINOMYCES BOVIS. 



The true nature of Actinomyces bovis was first recognised by 

 Bellinger in cattle in 1877. The disease is characterised by the 

 formation of specific tumours tending to suppuration, the lesions 

 being frequently located in the jaw bones and subcutaneous con- 

 nective tissue of the maxillary region, and are commonly known as 

 wen, osteosarcoma, lumpy-jaw, etc., and when affecting the tongue as 



