414 PATHOGENIC MICROCOCCI 



mors " in the parenchymatous organs. These vary in size from that 

 of a millet seed to that of a pea, and undergo caseation. They con- 

 tain the micrococcus and are infectious. Mammals die in from nine 

 to fifteen days ; birds in from one to three or four, and without the 

 formation of the characteristic granuloma, but with general infec- 

 tion of the blood. Cultures which have been kept for several months 

 retain their pathogenic power. 



MICROCOCCUS OF BOVINE MASTITIS (Kitt). 



Obtained by Kitt (1885) from the udder of cows suffering from mastitis 

 and giving- milk mixed with pus. 



Morphology. Micrococci, having a diameter of 0.2 to 0.5 >u, solitary, 

 united in pairs, in irregular groups, and occasionally in chains. 



Stains with the aniline colors. 



Biological Characters. Does not liquefy gelatin. Upon gelatin plates 

 forms spherical, translucent, glistening colonies, the size of a hemp seed to 

 that of a pin's head ; in gelatin stab cultures a nail-shaped growth occurs, 

 the mass at the point of puncture being opaque and of a white color. Upon 

 potato, colonies are quickly developed which have a grayish -white or dirty 

 yellow color, and after a few days have a shining, wax-like appearance. 

 G-rows rapidly in milk, causing an acid reaction ; in six hours in the incu- 

 bating oven the milk is pervaded by the micrococcus, or in twelve hours at 

 20 C. 



Pathogenesis. Injection of pure cultures, suspended in distilled water, 

 into the mammary glands of cows, produces typical, acute, purulent mas- 

 titis (Kitt). The micrococcus produced the same result after having been 

 cultivated in artificial media for a year. Subcutaneous inoculations in cows, 

 pigs, guinea-pigs, rabbits, and mice were without result. Injections into 

 the mammary gland of goats were also without effect. 



MICROCOCCUS OF BOVINE PNEUMONIA (?). 



Isolated by Poels and Nolen (1886) from the lungs of cattle suffering 

 from ' ' Lungenseuche " (infectious pleuro-pneumonia of cattle). 



Morphology. Micrococci, varying considerably in size average dia- 

 meter 0.9 #; solitary, in pairs, or in chains containing several elements; sur- 

 rounded by a transparent capsule, which stains with difficulty. 



Stains with all the aniline colors, and with difficulty by Gram's method. 



Biological Characters. Does not liquefy gelatin, and grows like the ba- 

 cillus of Friedlander in gelatin stab cultures (nail-shaped growth). In gela- 

 tin plates the colonies are spherical, white, and have a very faint yellowish 

 tinge. Grows more rapidly on agar in the incubating oven, and upon po- 

 tato in the form of a very pale-yellowish layer. Is destroyed by a tempera- 

 ture of 66 C. maintained for fifteen minutes. 



Pathogenesis Pure cultures injected into the lungs of dogs, rabbits, 

 and guinea-pigs are said to give rise to pneumonic inflammation, and simi- 

 lar results were obtained by injection into the trachea of dogs and by in- 

 halation experiments. Injection of a pure culture into the lungs of a cow 

 caused extensive pneumonic changes ; but these did not entirely correspond 

 with the appearances found in the lungs of cattle suffering from infectious 

 pneumonia. Cattle inoculated with a pure culture, by means of a sterilized 

 lancet, did not fall sick, but are believed by Poels and Nolen to have been 

 protected from the disease by such inoculations. 



The specific relation of the micrococcus above described to the disease 

 with which it was associated, in the researches of the authors mentioned, has 

 not been established by subsequent investigations. 



