614 TRICHOMYCETES, ACTINOMYCETES, HYPHOMYCETES 
fused with true actinomycotic infection.^ The earhest stage of the 
infection is a small nodule not unlike a tubercle; microscopically it is 
made up of small round cells, epitheloid cells and giant cells. This 
soon softens and sinuses often are formed, through which tb.e pus 
escapes. The surrounding connective tissue proliferates rapidly, form- 
ing a dense encapsulation through which invasion of neighboring tissue 
takes place; often the disease spreads in one direction while simul- 
taneously the older lesion becomes cicatrized. Death frequently occurs 
through secondary invasion by adventitious bacteria. 
Actinomycosis is not a contagious disease and it is practically 
impossible to infect experimental animals, as guinea-pigs and rabbits, 
with the virus. Wright^ has been unable to produce progressive 
actinomycosis in these animals, although he succeeded occasionally 
in inducing a localized purulent nodule formation in guinea-pigs, in 
which granulation tissues and colonies of Actinomyces appeared, some 
of which showed poorly defined clubs. 
Fig. 90. — Mucor sporangium. 
The disease is stated to be transmitted through wounds caused by 
certain grains, particularly those which possess barbs, but the evidence 
is not wholly convincing. 
The diagnosis of actinomycosis is best made by microscopic exami- 
nation of sputum, or the pus from the lesions. The demonstration 
of the characteristic "driisen" with their club-shaped peripheral 
filaments is conclusive. Sometimes actinomycotic pus does not con- 
tain granules; if the sinus be curetted, the organisms will frequently 
be demonstrable in the scrapings, even though they are absent from 
the pus. 
Mycetoma (Nocardia madurse, Discomyces madurse or Madura 
Foot).— The term IMycetoma is a generic one, including purulent 
inflammations of the foot chiefly, but also of the hands and less com- 
» Davis: Jour. Am. Med. Assn., 1920, 74, 317. 
2 Loc. cit. 
