. A text-book upon the pathogenic Bacteria and Protozoa for students of medicine and physicians. Bacteriology; Pathogenic bacteria; Protozoa. 312 Suppuration temperatures above 8°C. and below 4S°C., the most rapid develQp- ment being at about 37°C. Colonies.âUpon the surface of gelatin plates the colonies appear as small whitish points, after from twenty-four to forty-eight hours, rapidly extending to the surface and causing extensive liquefaction of the medium. The formation of the yellow pigment can be best observed near the center of the colonies. Under the microscope the colonies appear
. A text-book upon the pathogenic Bacteria and Protozoa for students of medicine and physicians. Bacteriology; Pathogenic bacteria; Protozoa. 312 Suppuration temperatures above 8°C. and below 4S°C., the most rapid develQp- ment being at about 37°C. Colonies.âUpon the surface of gelatin plates the colonies appear as small whitish points, after from twenty-four to forty-eight hours, rapidly extending to the surface and causing extensive liquefaction of the medium. The formation of the yellow pigment can be best observed near the center of the colonies. Under the microscope the colonies appear as- round disks with circumscribed, smooth edges. They are distinctly granular and dark brown. When the colonies are grown upon agar-agar plates, the formation of the pigment is more distinct. Gelatin Punctures.âIn gelatin the growth occurs along the whole length of the puncture, causing an extensive liquefaction of the medium in the form of a long, narrow, blunt- pointed, inverted cone, sometimes described as being like a stocking, full of clouded liquid, at the apex of which a collection of golden or orange-yellow precipitate is always present in Staphylococcus aureus. It is this precipitate in particular that gives the orgaiiism its name, " golden ; Agar-Agar.âThe growth of the golden staphylococcus upon agar-agar is subject to considerable variation in the 'quantity of pig- ment produced. Sometimes, perhaps rarely, it is golden; more commonly it is yellow, often cream color. Along the whole line of inocula- tion a moist, shining, usually well-circum- scribed growth occurs. When the develop- ment occurs rapidly, as in the incubator, it exceeds the rapidity of color production, so that the center of the growth is distinctly colored, the edges remaining white. Potato.âUpon potato the growth is luxuriant, Staph- ylococcus aureus producing an orange-yellow coating over a large part of the surface. The potato cultures may give off a sour odor.
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