NOT DESCRIBED IN SECTIONS V. AND VI. 417 
acquires a yelluw color, while the periphery remains of a dirty-white or 
grayish color. Blood serum is liquefied by this micrococcus. 
Pathogenesis.—A few drops of a pure culture injected subcutaneously or 
into the mammary gland of sheep cause an extensive inflammatory oedema 
and the death of the animal in from twenty-four to forty-eight hours. A 
cubic centimetre injected into the mammary gland of a goat produced no re- 
sult; the horse, the calf, the pig, the cat, chickens, and guinea-pigs also proved 
to beimmune. Subcutaneous injections in rabbits produce an extensive ab- 
scess at the point of inoculation, 
STREPTOCOCCUS OF MASTITIS IN COWS. 
Obtained by Nocard and Mollereau (1887) from the milk of cows suffering 
from a form of chronic mastitis (mammite contagieuse). 
Morphology.—Spherical or oval cocci, a itttle Tees than one in diameter, 
usually united in long chains. 
Stains with the usual aniline colors and also by Gram’s method. 
Biological Characters.—An aérobic and facultative anaérobic, non- 
liquefying streptococcus. Grows in the usual culture media at the room 
temperature. Develops rapidly in milk or in bouillon at a temperature of 
16° to 30°C. The milk of a cow suffering from the form of mastitis produced 
by this micrococcus, when drawn with proper precautions in sterilized test 
tubes, at the end of twenty-four hours is acid in reaction; the lower two- 
thirds of the tube is filled with an opaque, dirty-white, homogeneous deposit, 
and above this is an opalescent, serous fluid of a bluish or dirty-yellow or 
slightly reddish color, according to the age of the lesion. A drop of this 
milk examined under the microscope shows the presence of the streptococcus 
in great numbers. The addition of two to five per cent of glucose or of gly- 
Fic. 97.—Streptococcus of mastitis in cows (Nocard). 
eerin to bouillon makes it a more favorable culture medium; the reaction 
should be neutral or slightly alkaline, as this streptococcus does not grow 
readily in an acid medium, although it produces an acid reaction in media 
containing sugar, the acid formed bene ee In gelatin stab cultures the 
growth upon the surface is scanty, in the form of a thin pellicle around the 
point of puncture; along the line of inoculation minute, opaque, granular 
colonies are developed, which, being closely crowded, form a thick line with 
jagged margins. Sse 
nagar stab cultures the growth is similar but more abundant. Upon 
the surface of nutrient gelatin, agar, or blood serum a large number of mi- 
a4 
