. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . h is a mixture of one-third human or animal blood serum orascitic or pleuritic fluid and two-thirds bouillon, or nutrient agarstreaked with human, horse, or rabbit blood. Growth on Agar.—Cultivated on plain nutrient agar, after twenty-four to forty-eight hours at 37° C, the deep colonies are hardly visibleto the eye. Under the microscope they appear light yellow or brownin color and finely granular. The surface colonies are larger, equaling,in size those of streptococci, but are usually more transp
. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . h is a mixture of one-third human or animal blood serum orascitic or pleuritic fluid and two-thirds bouillon, or nutrient agarstreaked with human, horse, or rabbit blood. Growth on Agar.—Cultivated on plain nutrient agar, after twenty-four to forty-eight hours at 37° C, the deep colonies are hardly visibleto the eye. Under the microscope they appear light yellow or brownin color and finely granular. The surface colonies are larger, equaling,in size those of streptococci, but are usually more transparent. Ifblood serum or ascitic fluid is added to the agar the individual coloniesare larger and closer together, and the growth is more distinct in con-sequence and of a grayish color. The surface colonies are almost circularin shape under a magnification of 60 diameters, finely granular instructure, and may have a somewhat darker, more compact centre,surrounded by a paler marginal zone. With high magnification cocciin twos and short rows often distinctly separated are seen at the Fig. 107.—Pneumocoocus from bouillonculture, resembling streptococcus. Fig. 108.—Pneumococci stained for cap-sule by Huntoons method. (Huntoon.) Growth on Blood Agar.—^The colonies on blood agar are greenish andno hemolysis is present. This is a useful characteristic in isolatingpneumococci from sputum, although many streptococci give similarcolonies. Methemoglobin is produced in broth cultures as shown onaddition of freshly washed red corpuscle suspensions. Growth on Blood Serum.—^The growth on Lofilers blood-serum mixtureis very similar to that on agar, but somewhat more vigorous and char-acteristic, appearing on the surface as a delicate layer of dew-like drops. Growth in Bouillon.—In bouillon, at the end of twelve to twenty-four hoursin the incubator, a slight cloudiness of the liquid will be found to have beenproduced. On microscopic examination cocci can be seen to be arra
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