(h) Perform an autopsy on the dead pig; note the pathologic changes, and prepare cultures, smears, and sections from the organs and from the point of inoculation.

VI. INFLUENZA.

1. Prepare blood-agar tubes by smearing the surface of a ordinary agar-tube with a drop of blood

obtained aseptically from man, rabbit, guinea-pig, pigeon, or frog.

2. Break up a distinctly purulent portion of influenza sputum in 1 or 2 c. c. of bouillon, and spread a loopful of the suspension over the surface of the blood-agar tube.

3.

Place in the incubator and examine at the end of from eighteen to twenty-four hours.

4. The influenza colonies appear as minute colorless, glassy, transparent points, resembling drops of dew. They are barely visible to the unpractised eye, and require a low magnifying power to be seen clearly.

5. Study the morphology and biology of the organisms in one of these colonies. They should not grow on ordinary media, and should have the morphology of the influenza bacteria.

6. Prepare smears from one of the purulent

masses in the sputum. Stain in very dilute carbolfuchsin for five to ten minutes, or in Löffler's methylene-blue heated to the steaming-point. The influenza bacteria are very small, short, with

FIG. 77.-Bacterium influenzæ cover-glass preparation of sputum from a case of influenza, showing the bacteria within the leucocytes; highly magnified (Pfeiffer).

round ends, are often present in large numbers, and are frequently within the pus cells. They may occur in pairs, and then resemble cocci. The ends are usually more deeply stained than the central portions.

FIG. 78.-Bacillus typhosus, from a twenty-four hour agar culture; × 650 (Heim).

FIG. 79.-Bacillus coli, from an agar culture; X 1000 (Itzerott and Niemann).

of Bacillus typhosus and Bacillus coli. Some of the differences between them are indicated below:

2. Study sections of spleen, intestinal lesions, mesenteric lymph-glands, etc., from a human typhoid autopsy. Stain with carbol-thionin-blue or carbol-fuchsin.

3. Widal Reaction in Typhoid Fever. If the blood-serum of a person suffering with typhoid fever or of one who has recently recovered from it