ACTINOMYCOSIS AND ALLIED DISEASES. 



resemblance to the actinomyces, are present. These may have 

 a yellowish or pinkish colour, compared from their appearance 

 to fish roe, or they may be black like grains of gunpowder, and 

 may by their conglomeration form nodules of considerable size. 

 Hence a pale variety and a black variety of the disease have 

 been distinguished ; in both varieties the granules mentioned 

 reach a rather larger size than in actinomycosis. These two 

 conditions will be considered separately. 



Pale Variety. — When the roe-Uke granules are examined 

 microscopically, they are found, like the actinomyces, to show 

 in their interior an abundant mass of branching filaments with 

 mycelial arrangement (Fig. io6). There may also be present at 



the periphery club-like struc- 

 tures, as in actinomyces; some- 

 times they are absent. These 

 structures often have an elon- 

 gated wedge shape, forming an 

 outer zone to the colony, and 

 in some cases the filaments can 

 be found to be connected with 

 them. Vincent obtained cul- 

 tures of the parasite from a 

 case in Algiers, and found it 

 to be a distinct species : it is 

 now known as the sti-eptotlirix 

 madiircB. Morphologically it 

 closely resembles the actino- 

 myces, but it presents certain 

 differences in cultural characters. In gelatin it forms raised 

 colonies of a yellowish colour, with umbilication of the centre, 

 and there is no liquefaction of the medium. On agar the 

 growth assumes a reddish colour; the organism flourishes well 

 in various vegetable infusions in which the actinomyces does 

 not grow. On all the media growth only takes place in aerobic 

 conditions. Experimental inoculation of various animals has 

 failed to reproduce the disease. There is therefore no doubt 

 that the streptothrix madurse and the actinomyces are distinct 

 species. 



Black Variety. — There has been considerable discussion 

 regarding the relation of this variety of the disease to that just 



Fig. io6. — Streptathrix ynadttrce, show- 

 ing branching filaments. From a culture 

 on agar. Stained with carbol-thionin-blue. 

 X looo. 



