SPECIFIC INFECTIOUS DISEASES PRODUCED BY COCCI 227 



is not very evident, if present, and the cells are usually in pairs or 

 tetrads. There is some evidence that this organism should be 

 grouped as a Sarcina, rather than as a Micrococcus, while in many 

 respects it resembles the Micrococcus aureus. It stains readily 

 with anilin dyes, and is gram-positive. 



Isolation and Culture. M. ascoformans may be isolated in 

 pure culture from the characteristic lesions, or in mixed infections 

 it may be secured by plating. In most of its cultural characters 

 it resembles a weakened strain of M. aureus. Gelatin colonies 

 are small, and cause slight liquefaction and cupping of the medium 

 when at the surface. In gelatin stab the growth is filiform and 

 white, followed by a slow, crateriform liquefaction. The colonies 

 on agar are scarcely visible in most strains, although more vigorous 

 types have been described. On potato the growth is yellowish and 

 has an aromatic odor. 



Physiology. This organism produces a small amount of gelat- 

 inase, as evidenced by the liquefaction of the gelatin. 



Pathogenesis. Experimental Evidence. Guinea-pigs injected 

 with M. ascoformans generally succumb to septicemia. Mice 

 are not susceptible. Sheep and goats develop ulcers at the point 

 of inoculation. Injection into the horse usually results in sup- 

 puration, but occasionally the typical botryomycomata are de- 

 veloped. Whether or not this is a variety of M. aureus is 

 unsettled, but it seems probable that it is a distinct species. 



Character of Disease and Lesions Produced. The lesions 

 resemble superficially certain fibromata and other neoplasms. 

 The infection usually takes place where the surface of the skin 

 has been abraded, as by harness, through wounds at castration, 

 on the udder, and elsewhere on the body. The tissues involved 

 become grayish-red, then lardaceous, and eventually form a mass 

 resembling a fibroma. These sometimes reach considerable size. 

 Metastatic infection through the lymph-channels may result in 

 the involvement of considerable areas and infection of the internal 

 organs, particularly the lungs. 



Immunity. Methods of developing immunity have not been de- 

 vised. It is possible that autogenic vaccination might be of value. 



Transmission. As noted above, infection generally occurs 

 through wounds or abrasions of the skin. 



