SECTION XVII— PART 3 
THE STREPTOTHRICOSES 
The organisms belonging to the genera Streptothrix, 
Actinomyces, Discomyces and Nocardia as named by 
various authors have in common the power to produce 
local chronic inflammation of gradually spreading char- 
acter and chronic course. Their most conspicuous repre- 
sentative, the ray fungus, is best Imown as the producer 
of lumpy jaw in cattle and as an occasional pathogen in 
man. Other members of the group cause certain lymph- 
channel disease in domestic animals and pulmonary dis- 
ease in man. Pathogenic power, it is believed, lies in 
the ability of these organisms to colonize and irritate, 
thus producing continuously enlarging tumefactions, no 
evidence being at hand that any of them produce a toxin 
either in their surroundings or within their own bodies. 
Because of their constant irritation, bacterial mixed in- 
fection often ensues so that purulent degeneration may 
occur at the original site of disease and thence may spread 
via the blood vessels, or by continuity of tissues or, if the 
mucous membrane of the pharynx be diseased, by the air 
passages. 
The study of the genesis of actinomycosis is by no 
means a closed one. While it is believed that pastures 
and fodder carry the organism and that it gains access 
to the tissues by passing into small wounds that are made 
by sharp sticks or grain beards, the exact origin of the 
disease is not understood. The original lesion is cer- 
tainly trifling and the fully developed one may not be 
discoverable until it is well under way and causes external 
deformity. Even when sloughing has occurred, the dis- 
ease is not very communicable. The method of contrac- 
tion of lymphatic streptothricosis in cattle is believed to 
be from other cases via sldn wounds or if abrasions be 
567 
