364 PATHOGENIC BACTERIA. 



fine round black or pink bodies, described, when black, 

 as resembling gunpowder ; when pink, as resembling 

 fish-roe. It is the detection of these particles upon 

 which the diagnosis rests, and upon which the divis- 

 ion of the disease into the melanoid and pale varieties 

 depends. 



The progress of the disease causes an enormous size 

 and a peculiar deformity of the affected part. The mal- 

 ady is generally painless. 



The micro-organismal nature of the disease was early 

 suspected. In spite of the confusion caused by some 

 who confounded the disease with and described it as 

 "Guinea-worm," Carter held that it was due to some 

 indigenous fungus as early as 1874. Boyce and Surveyor 

 believe that the black particles of the melanoid variety 

 represent a curious metamorphosis of a large branching 

 septate fungus, and that the white particles of the other 

 variety are the remains of a lowly-organized fungus and 

 of caseous particles. 



Kanthack tried to prove the identity of the fungus 

 with the well-known actinomyces, but there seems to 

 be considerable doubt about the correctness of his view. 



Vincent succeeded in isolating the micro-organism 

 by puncturing one of the nodes with a sterile pipette, 

 and has cultivated it upon artificial media. Acid vege- 

 table infusions seem suitable to its growth. It develops 

 scantily in bouillon at the room-temperature, better at 

 37 C. — in from four to five days. In twenty to thirty 

 days the colony attains the size of a little pea. 



In the liquid media the colonies which cling to the 

 glass, and thus remain near the surface of the medium, 

 develop a rose- or bright-red color. 



Cultures in gelatin are not very abundant, are colorless, 

 and are unaccompanied by liquefaction. 



Upon the surface of agar-agar strikingly beautiful 

 rounded, glazed colonies are formed. They are at first 

 colorless, but later become rose-colored or bright red. The 

 majority of the clusters remain isolated, some of them 



