37°.

PLATE 13.

Bacterium pestis.

Lehm. and Neum.

I. Streak culture (ascites-glycerin-agar), three days at

II. Streak culture (agar), forty-eight hours at 37°. (After a culture of Dr. Dieudonné, preserved with formalin.) The streak was made with the juice direct from a bubo. The transparent, dewdrop-like growth is characteristic.

III. Stab culture (gelatin), six days at 22°. The growth consists of minute, waxy, markedly elevated colonies, which become confluent; also the same upon the gelatin plate (v, b).

IV. Plate culture (gelatin), six days at 22°. × 60. (a) Deep colony; (b) superficial colony.

V. Plate culture: (a) Glycerin-agar, three days at 37°. Natural size. Superficial colonies. Superficial colonies. (b) Gelatin, six days at 22°. Natural size. Superficial colonies. Compare what is said under Fig. III.

VI. Plate culture (agar), forty-eight hours at 37°. X 60. Superficial colonies. They correspond to the dewdrop-like colony in the agar streak culture (11). (a) Younger, (b) older colonies.

VII. Plate cultures, forty-eight hours at 37°. X 60.

(a) Ordinary agar

(b) Glycerin-agar

(c) Ascites-glycerin-agar

Superficial colonies.

(d) Ascites-glycerin-agar, deep colony.

The crumbly character of cultures after being cultivated in contrast to very fresh cultures is to be noted (compare VI).

VIII. Microscopic preparation, three days at 37° on glycerin-agar. X 1000. Stained with fuchsin. Involution

forms.

IX. Microscopic preparation: Smear from the juice of a bubo. X 1000. Stained with methylene-blue. (From a preparation of Dr. Dieudonné.)

X. Microscopic preparation: (a) Ordinary agar, twenty-four hours at 37°. × 1000. Stained with fuchsin. (b) Ordinary bouillon, twenty-four hours at 37°. X 1000.