MOLD OR HYPHOMYCETE GROUP 407 



man. Inoculation of pure cultures into mice and white rats 

 liives rise to abscesses at the point of inoculation, and the infec- 

 tion gradually extends. Guinea-pigs and rabbits are infected 

 with greater difficulty. An infection somewhat resembling farcy 

 develops upon inoculation into the horse. 



Character of Disease and Lesions Produced. The infection is 

 usually benign in character in the horse. There is no fever reac- 

 tion during the course of the disease. Nodules develop which are 

 generally spherical and sharply delineated. These nodules scarcely 

 rupture, but pus accumulates at the center, the skin above is 

 thinned and softened, serum exudes from the surface, the hair is 

 loosened, and a crust holding the hairs together is formed. The 

 ulcers are crateriform, and usually contain a little creamy pus. 

 Healing is accomplished by granula- 

 tion. Sections of nodules from labor- 

 atory animals reveal the organism in 

 the tissues. 



Immunity. No toxins have been 

 demonstrated for this organism. 

 Widal has shown the presence of 

 agglutinins for the spores in the 

 blood of infected individuals. No Fig. 182. Sp&rotrichum 

 method of immunization, based upon teurmanm, in a section of a 

 the organism or its products, has mesenteric abscess of a rat 



(adapted from Fiehtz). 

 been developed. 



Bacteriological Diagnosis. This may be accomplished by 

 animal inoculation, thus securing the organism in pure culture. 

 Widal claims that the agglutination of spores will take place in 

 dilutions as high as 1:800, but the same reaction takes place in 

 lower dilutions with the blood-serum of individuals having ac- 

 tinomycosis. Bloch found that a bouillon filtrate from an old 

 culture would in man give the von Pirquet cutaneous reaction, as 

 was described in the chapter on Bacillus tuberculosis. 



Transmission. The disease is transmitted by intimate contact 

 usually. It has been found to be transferred from animals to man. 

 Probably the organism usually gains entrance through abrasions of 

 the skin. 



