THE EXAMINATION OF CULTURES 49 
a stained (carbol fuchsin) cover-glass preparation. Describe the 
appearance of the bacteria (§ 35). Examine the fermentation 
tubes and indicate the quantity of gas. 
Examine microscopically in hanging-drop preparations the 
bacteria from the glucose bouillon culture, 
Make a stained cover-glass preparation from the milk cul- 
ture. Stain with carbol fuchsin.. 
76. A few points to be observed in studying cultures on 
special mediay (2) /ofato. Note carefully the extent and 
color of the growth and its consistence. 
(4) Mitk. Note whether or not the general appearance and 
odor of the milk have been changed, and observe whether the 
casein has been coagulated, giving a firm, solid coagulum, or 
precipitated. Is the coagulum covered with a liquid (serum)? 
if so, is it clear or milky? Is there any appearance suggestive 
of saponification? Determine its consistence, its chemical reac- 
tion as indicated by litmus paper (§ 27), and give as descriptive 
a name as possible to its odor. 
(¢) Litmus milk. Note especially whether there has been 
any change in color since inoculation. Observations similar 
to those on the plain milk should also be made. 
(2) Glucose agar. Note the character and number of col- 
onies within the agar, and the presence, if any, of gas bubbles. 
Are there few or many of them? 
(¢) Bouillon containing sugars in test tubes. Note carefully 
the appearance of the bouillon, but especially its chemical 
reactions as indicated by the litmus paper (§ 27). 
(/) Bouillon containing sugars in fermentation tubes. Ob- 
serve the character of the growth in each tube (whether the 
liquid is faintly or heavily clouded, turbid, contains flakes, etc.), 
—§in (x) the open bulb and in (2) the closed branch of the 
fermentation tube. Note the presence or absence of a mem- 
brane on the surface of the liquid in the open bulb. Is there 
a sediment in the bottom of the tube? If so, describe its 
general appearance and consistence. Note the presence or 
