646 



Acliuoiuycusis. 



Pathogenicity. Tims far it has been impossible to produce 

 absohitely positive results in the transmission of the disease 

 from man to animals. These experiments have usually con- 

 sisted in the subcutaneous administration of colonies of the 

 parasite from man to animals. Submucous 

 membrane inoculations and administration 

 into the abdominal cavity or the anterior of 

 the eje have also been tried. Johne, Ponfick, 

 Israel, Rotter and Hanau believed to have 

 obtained positive results in calves and guinea 

 pigs in which nodules, ranging in size from 

 a pea to that of a hazelnut, developed on the 

 serous membranes. These lesions, however, 

 were invariably of a benign and never of a 

 progressive character. (Similar nodules are 

 observed to develop when other foreign 

 bodies had been introduced into the serous 

 cavities.) Affanassjew, and subsequently 

 also Israel and Wolff attempted experimental 

 infection with pure cultures which, however, 

 were also without convincing results, al- 

 though Wright observed growth and club for- 

 mations in the filaments found in the center 

 of the resulting local abscesses. 



Biagi succeeileil in detecting an emlogenes toxin in cul- 

 tures, which proilnceil maiasnuis in animals while I'oncet, 

 Laconniic & Thevencit failed to i< cognize the presence of 

 soluble toxins. 



Natural infecticn takes place through 

 the mucous membranes, usuall}^ that of the 

 mouth, tlirough the medium of gramineae, 

 ]')articularly the awns of tlie heads of barley 

 (Joline). Bostrom found in the examina- 

 tion of 5 cases of human actinom3rcosis por- 

 tions of awns, only 0.2 mm. in length, im- 

 bedded in the more recent portions -of the 

 tumors, in the center of masses of leucocytes 

 and granulation tissue, which in turn were 

 surrounded on all sides by mycelium and 

 characteristic fungus colonies. In one case 

 he demonstrated that the fungus had orig- 

 inally existed in the air spaces of the awns 

 where it had proliferated, penetrated the 

 walls of the air spaces and found its way 

 into the surrounding tissue elements. 

 _ This result of Bostrom 's microscopical examination ex- 

 plains the maiiner of infection in these and similar cases. Awns 

 of grasses which accidentally come in contact with the mucous 

 membrane of the upper digestive tract force themselves through 



Fig. 101. Potato Cul- 

 ture of fflreptotliri.e 

 acliiioiiiiji-rs six weeks 

 old. 



