to have taken place, but at the end of the second day there is a slight clouding and a meager precipitate. The organism seems to maintain its vitality somewhat longer in bouillon than in other culture-media.

Pathogenesis.-The organism seems to be scarcely pathogenic for animals. Kirchner was able to kill a guineapig by intrapleural injection, and Neisser, who performed numerous experiments upon mice, guinea-pigs, and rabbits,

only once succeeded in producing a fatal infection, by the intraperitoneal injection of 0.4 c.c. of bouillon culture. In this animal the cocci were found in all the internal organs. As has already been said, the organism is found associated with superficial inflammatory conditions of the mucous membrane. It is probably most common in influenza. It has also been found in conjunctivitis, in bronchitis, in whooping-cough, and in pneumonia.

CHAPTER IX.

CHANCROID.

THE BACILLUS DUCREYI.

General Characteristics.-A small, ovoid streptobacillus, with rounded, deeply staining ends, non-motile, non-flagellate, non-sporogenous; aërobic and optionally anaërobic, non-chromogenic, staining by ordinary methods, but not by Gram's method, cultivable on special media only and pathogenic only for man and certain monkeys.

The chancroid, soft chancre, or non-specific sore, as it is called, is a common venereal affection of both sexes, most frequent among those who give little attention to cleanliness. It is characterized by the appearance of a soft reddish papule, which makes its appearance usually upon the genital organs, rarely upon other parts of the body, soon after the infection, and soon becomes transformed to an ugly ulceration whose usual tendency is toward slow and persistent enlargement, though in different cases it may be indolent, active, phagedenic, or serpiginous. The inguinal or other nearby lymph-nodes early enlarge and soon soften and ulcerate. The disease is, therefore, extremely destructive to the tissues invaded, though no constitutional involvement ever takes place.

Specific Organism.-In 1889 Ducrey* described a peculiar organism whose presence he was able to demonstrate with great constancy, sometimes in pure culture, in the lesions of chancroid, and which he believed to be the specific organism of the affection. Unna† later described an organism resembling that of Ducrey, and the later observations of Krefting, Peterson, § Nicolle, || Cheinisse,** and * "Congrès. Inter. de Dermatol. et de Syphiligr.," Paris, 1889; "Compt rendu," p. 229.

"Monatschr. f. praktische Dermatologie," Bd. XIV, 1892, p. 485. "Archiv. f. Dermatol. u. Syphilol.," 1897, p. 263; 1897, p. 41. § "Centralbl. f. Bakt.," etc., 1893, XII, p. 743.

$ "Med. Moderne," Paris, 1893, IV, p. 735.

** 46 Ann. de Dermat. et de Syphil.," Par., 1894, p. 272.

Davis* have abundantly confirmed the observations of Ducrey and Unna, and proved the identity of the two micro-organisms and their specificity for the disease.

Morphology. The organism is commonly described as a" streptobacillus.' It is very small, short, and ovoid in shape, and occurs habitually in longer or shorter chains. Each organism measures about 1.5 +0.5 μ. The ends are rounded and stain deeply. In pure cultures long undivided filaments, at least twenty times as long as the individual bacilli, are not uncommon. There seems to be no relation between the cells and the bacilli. As a rule, they are free, sometimes they are inclosed in leukocytes.

X 1500 (Davis).

(Photo

Fig. 138. Smear of pus of chancroid of penis stained with carbolfuchsin and briefly decolorized by alcohol. micrograph by Mr. L. S. Brown.)

Staining. The organisms are somewhat difficult to stain, as they do not retain the color well, giving it up quickly when washed. They do not stain by Gram's method.

Cultivation. The first successful isolation and cultivation of the organism seems to have been by Benzançon, Griffon and Le Sours† upon a culture-medium consisting of rabbits' blood 1 part, and agar-agar 2 parts. Davis has been equally successful in cultivating the organism upon this

medium.

His method was as follows:

"Tubes of 2 per cent. agar, reaction + 1.5, were melted

*

"Jour. Med. Research," 1893, IX, p. 401.

Ann. de Dermat. et de Syphiligr.," 1901, II, p. 1.
Loc. cit.

and mixed with fresh rabbits' blood drawn under aseptic precautions, in the proportion of two-thirds agar to onethird blood, and slanted while in a fluid state. At a later period tubes of rabbits' blood-serum uncoagulated, also rabbits' blood bouillon, one-third blood to two-thirds bouillon, were used, and gave equally satisfactory results. By employing small tubes of freshly drawn human blood pure cultures were obtained in several instances from genital lesions direct without any special cleansing of the ulcerated surface. This, I believe, is the best medium for obtaining cultures from a source open to contamination, the fresh

Fig. 139. Culture from ulceration on monkey resulting from inoculation of culture from a case of chancroid of finger, first generation. Stained with carbol-fuchsin and briefly decolorized by alcohol. Culture of twenty-four-hours' growth in rabbit's bouillon. X 1500 (Davis). (Photomicrograph by Mr. L. S. Brown.)

blood apparently inhibiting to a certain extent the growth of extraneous organisms."

No growth takes place upon ordinary culture-media under either aërobic or anaerobic conditions.

Cultures are best obtained by puncturing an unopened bubo with a sterile needle and planting the pus directly and immediately upon the special medium which should have been warmed in the incubator so that the pus is not chilled. In this way pure cultures may be secured, which are difficult to get from the soft sore itself.

Colonies. The colonies appear upon the appropriate media in about twenty-four hours, and attain their complete

development in about forty-eight hours. They are at first round bright globules, and later become grayish and opaque. They measure 1 to 2 mm. in diameter and never become confluent. They are difficult to pick up with the platinum wire, tending to slide over the smooth surface of the medium. Vital Resistance. The organisms seem to possess little vitality, their life in artificial culture being limited to a few days. Frequent transplantation enabled Davis to carry them on to the eleventh cultural generation.

Pathogenesis. The organism is pathogenic for man and certain monkeys (macacus), but not for the ordinary laboratory animals. The organism can be found in large numbers in both the genital and extragenital chancroidal lesions, and usually in small numbers in the pus from chancroidal buboes. It has not been encountered elsewhere. Lenglet isolated the organism in pure culture, and by inoculation with his cultures reproduced the lesions in man.

**Bull. Med.,” 1898, p. 1051; "Ann. de Dermatol. et de Syph.," 1901, t. II. D. 209.