656 THE PARASITIC HYPOMYCETES 



never becomes cloudy. On gelatin they form small, spherical, star-like colonies ; 



their growth on potato consists of hard, dry, scaly masses. The appearance of a 

 culture however and also the colour vary to some extent with 

 the different species and with age. In old cultures on solid 

 media numerous aerial hyphse bearing chains of conidia project 

 from the surface : during germination the envelope of the 

 spore bursts, and from it there originates a young filament 

 which in turn ramifies. Reproduction may also take place 

 by transverse division of the filaments. So that according 

 to the age of the culture, microscopical examination may 

 show branched forms, streptococcal-like chains, or small 

 filaments closely resembling the avian tubercle bacillus. In 

 view of this apparent pleomorphism it is not surprising that 

 observers were for a long time led astray in their investigations 



Minto the nature and identity of these parasites. 

 Organisms of the genus Discomyces stain in a manner similar 

 to that of the tubercle bacillus. 



I. DISCOMYCES BOVIS. (Hartz ; R. Blanchard.) 



Syn. Actinomyces bovis Bellinger and Hartz. Oospora 

 bovis Sauvageau and Radais. Nocardia actinomyces 

 Trevisan. [Streptothrix actinomyces Rossi Doria.] 



That cattle were subject to a peculiar disease charac- 

 FIG. 306. Fructifica-terized by the formation of large, hard, sarcomatous 

 tionof an Oospora. (After m asses in the tongue and iaw bones which had a tendency 



SaDouraud.) -111 i i i.inr i j_- * 



to break down and become purulent had for a long time 

 been recognized, but the cause of this disease was unknown until Bollinger and 

 Hartz showed that it was due to a specific parasite, to which they gave the 

 name Actinomyces bovis. Shortly afterwards Israel and Wolff found the same 

 organism in the pus of an empyema in the human subject. Since then a 

 very considerable number of cases of Actinomycosis in man have been recorded, 

 and the disease can no longer be regarded as a pathological curiosity. 



Infection with the parasite in man, as in cattle, may take the form of a swelling 

 of the jaw bone, but lesions localized in other tissues of the body and even generalized 

 infections are frequently seen, and may so closely resemble tuberculosis as to be 

 confounded with that disease. Infection of the lung (broncho-pneumonia, pleurisy) 

 and of the peritoneum is not uncommon. It is a difficult matter to diagnose the 

 disease on clinical evidence alone so that a microscopical examination of the pus, 

 sputum, etc. is of great assistance. 



Actinomycosis occurs also in animals other than cattle ; it has been found in pigs, 

 deer, sheep, horses, elephants, and other animals. 



Outside the body Discomyces bovis lives as a saprophyte on cereals, and infection 

 of cattle is thus easily accounted for. Man may become infected by handling corn 

 or by inhaling dust during threshing operations. Delearde produced an osteo- 

 sarcoma in the maxilla of a sheep by inoculating the bone beneath the periosteum 

 with a grain of barley infected with the parasite. 



1. Experimental inoculation. 



The earlier experiments made with cultures grown aerobically failed to 

 infect the inoculated animals (Bostrom). Israel and Wolff, however, were 

 able to infect rabbits by inoculating them with cultures grown anaerobically 

 [vide D. Israeli). Mertens inoculated a rabbit in the anterior chamber of 

 the eye and produced nodules containing clubbed forms of the parasite. 



Inoculations with pus from foci of actinomycosis in man have often given 

 positive results in guinea-pigs, rabbits and cows (Israel and others). Rabbits 

 die several months after being inoculated sub-cutaneously or intra-peritone- 



