454 A MANUAL OF BACTERIOLOGY 



bottom as liquefaction progresses. On potato a remark- 

 able growth develops ; at first brownish, it afterwards 

 becomes almost black, and is very thick or heaped up with 

 a much wrinkled surface, while later on it has the appear- 

 ance of being sprinkled with flowers of sulphur (Fig. 49). 

 In broth delicate woolly flocculi form. 

 Films from young agar cultures show 

 masses of tangled filaments, which appear 

 to be more or less branched, and stain 

 well with the ordinary anilin dyes and by 

 Gram's method ; with the latter the fila- 

 ments often appear somewhat beaded, 

 but no trace of rosette formation or even 

 of clubs is ever found in cultures (Fig. 50). 

 In pus, especially human, the filaments 

 can sometimes be seen if stained by 

 Gram's method with orange-rubin. Inocu- 

 lated into the peritoneal cavity of rabbits 

 " ^ and guinea-pigs the cultivated organism 

 reproduces the disease, numerous actino- 

 mycotic nodules forming in the peritoneum 

 and elsewhere. There is much doubt as 

 to the mode of spread of, and the infection 

 FIG. 49. Actino- of man with, the disease. It does not seem 

 myoes. Potato to be particularly contagious, and diseased 

 months old. * anc ^ healthy animals are often placed to- 

 gether without bad result ; it can, however, 

 be conveyed by direct inoculation, for calves inoculated 

 intraperitoneally with portions of diseased tissues die after 

 some weeks or months, with an abundant development 

 of actinomycotic nodules, as shown by the experiments 

 of Jone and Ponfick. Crookshank also infected a calf with 

 the material from a human case. Feeding experiments 

 give negative results. The view generally held is that 

 the organism occurs on cereals, straw, or roots, and gains 



