412 PATHOGENIC MICROCOCCI 



and along the line of puncture a series of round, milk-white or yel- 

 lowish masses form, which usually remain distinct, but may become 

 confluent. Upon the surface of agar the growth is similar to that 

 upon gelatin, or in streak inoculations may consist of a series of 

 spherical, white colonies. Upon cooked potato a thick, viscous layer 

 is formed of milk-white color ; the growth upon blood serum is also 

 abundant, especially in the incubating oven. This micrococcus is a 

 facultative anaerobic. 



Pathogenesis. Subcutaneous inoculation of a culture of this 

 micrococcus in minute quantity is fatal to white mice in from two to 

 six days. The animals remain apparently well for the first day or 

 two, then remain quiet and somnolent until death occurs. The cocci 

 are found in comparatively small numbers in the blood of the heart, 

 but are more numerous in the spleen, lungs, liver, and kidneys, from 

 which organs beautiful stained preparations may be made show- 

 ing the tetrads surrounded by their transparent capsule. Common 

 house mice and field mice are, for the most part, immune, as are the 

 rabbit and the dog. Guinea-pigs sometimes die from general infec- 

 tion, and sometimes a local abscess is the only result of a subcutane- 

 ous inoculation. 



MICROCOCCUS BOTRYOGENUS (Rabe). 



Synonyms. Micrococcus of " myko-desmoids " of the horse; Mi- 

 crococcus askoformans (Johne) ; Ascococcus Johnei (Cohn). 



First described by Bollinger (1870) ; morphological characters and 

 location in the diseased tissues described by Johne (1884) ; biological 

 characters determined by Rabe (1886). 



Is found in certain diffused or circumscribed growths in the con- 

 nective tissue of horses " myko-desmoids." 



Morphology. Micrococci, having a diameter of 1 to 1.5 /*, usu- 

 ally united in pairs. 



In the tissues the cocci are united in colonies of fifty to one hun- 

 dred yw in diameter, and these are associated in mulberry-like masses 

 visible to the naked eye. The separate colonies are enclosed in a 

 homogeneous, transparent envelope as in Ascococcus Billrothii. 

 This is not the case, however, in cultures in artificial media. 



Stains with the aniline colors. 



Biological Characters. In gelatin plate cultures spherical, 

 sharply defined, silver-gray colonies are developed ; later these have 

 a yellowish color and a metallic lustre, and the plate presents the ap- 

 pearance of being powdered with grains of pollen. It gives off a 

 peculiar fruit-like odor, reminding one of the odor of strawberries. 

 In gelatin stab cultures growth occurs along the line of puncture as 

 a pale grayish- white line, which later becomes milk-white ; an air 



