ACIDFAST ACTINOMYCETES 381 



They may be distinguished from the other pathogenic actinomy- 

 cetes by the readiness with which they may be cultivated on artificial 

 media, by their cultural characters, and particularly by their high 

 virulence for laboratory animals. In the latter respect, however, 

 there is considerable individual variation in strains and some strains 

 isolated from fatal human cases may produce only local and self- 

 limited lesions in experimental infections. Their relationship to the 

 acidfast bacteria is indicated not only by their acidfastness. Several 

 species, notably Nocardia asteroides, form a wrinkled mealy growth 

 of yellowish orange color which bears a very close resemblance to 

 that of the tubercle bacillus on solid media. The lesions of the 

 natural infection may also closely simulate tuberculosis; the experi- 

 mental infections are generally more acute than tuberculosis, produc- 

 ing more of a suppurative reaction and necrosis, with less granu- 

 lomatous reaction. But the close relationship is most clearly indi- 

 cated by the immunological reactions. Thus Nelson and Henrici 

 found that with complement-fixation reactions the acidfast actino- 

 mycetes showed a closer relationship to the acidfast bacteria than 

 they did to the non-acidfast actinomycetes. The possibility of cross 

 allergic reactions between tuberculosis and infections caused by acid- 

 fast species of Nocardia, as manifested by intradermal skin reactions, 

 has interested several investigators. Conclusions reached have been 

 somewhat contradictory. Drake and Henrici*' reinvestigated this 

 problem in experimentally infected guinea pigs and rabbits. Using 

 old tuberculin and a filtrate prepared from broth cultures of N. as- 

 teroides which they called asteroidin, as w^ell as several fractions of 

 the latter, they were not able to demonstrate any cross reactions to 

 tuberculin. 



Three species have been obtained from infections in animals: N. 

 farcinica from cattle, N. Caprae from goats, and A^. Canis from dogs. 



N. farcinica produces a disease of cattle characterized by a spread- 

 ing subcutaneous lymphangitis with localized abscesses, somewhat 

 resembling glanders in horses, and designated "farcin du boeuf" by 

 Nocard, who first described it and isolated the organism. It occurs in 

 France and on the island of Guadeloupe in the French West Indies, 

 but has also been reported from other parts of the world. The organ- 

 ism forms a pale yellow wrinkled growth on solid media, with a 

 powdery aerial mycelium in older cultures. No change occurs in milk 

 or gelatin. The organism is pathogenic for guinea pigs, cattle, and 

 sheep but not for other animals. 



N. Caprae, described by Silberschmidt, is very similar to the above; 

 it differs in forming a more whitish growth on solid media, a more 



