as also those of Stutzer and Hartleb, regarding a polymorphous saltpeter fungus are incorrect. Compare Fränkel (C. B. L. IV, 8, 62) and Gärtner (C. B. L. IV, 1, 52, 109).

Microscopic Appearance. Short rods, 1 μ long, 0.3– 0.4 μ thick. Stain poorly. When stained with warm gentian-violet solution and washed with a 10% solution of chlorid of sodium, a stained capsule surrounds the bacilli, which are unstained. With carbol-fuchsin the rods are gradually stained, the pointed ends escaping. Alkaline methylene-blue first stains the ends, then the central portion.

Motility is never observed. No growth occurs upon the ordinary nutrient media, rich in organic substances (bouillon, agar, gelatin), but it grows upon the following: Nitrite-agar, which contains pure sodium nitrite 2 gm., sodium bicarbonate 1 gm., potassium phosphate and agar 15 gm., water 1 liter; or nitrite solution, which contains: sodium nitrate 1.0, potassium phosphate 0.5, magnesium sulphate 0.3, sodium bicarbonate 0.5-1.0, sodium chlorid 0.5, a little iron sulphate, distilled water (distilled twice over permanganate) 1000. If soda is used instead of sodium bicarbonate, then also free CO2 must be present. The addition of more than 0.4% peptone, or of small quantities of sugar, prevents the growth and the production of nitrate.

Nitrite-agar Colonies.-Deep: granular, dense, small, sharply outlined, strongly refracting, appearing only after weeks. On the surface delicate, cloud-like, homogeneous, scarcely at all granular droplets develop equally slowly.

Nitrite-agar Stab Culture.-Somewhat more luxuriant, dirty white, greasy.

Isolation from Soil.-Numerous plates are prepared from nitrite-agar with larger and smaller quantities of soil suspended in it. After standing for three or four weeks at about 20°, test the plates to determine whether nitrate has been formed. Inoculate from a number of the smallest colonies into nitrite solution, and after about three weeks prepare new plates of nitrite-agar from the tubes which contain no nitrite, but nitrate. The pure culture should behave as follows: (1) A scarcely perceptible precipitate should appear, which rises as a column on shaking; (2)

upon gelatin and agar plates no colonies develop; (3) in tubes with nitrite solution the reaction for nitrite should disappear after about eight days.

Bacterium influenzæ (R. Pfeiffer). Lehm. and
Neum.

Literature.-R. Pfeiffer (Z. f. H. XII, 357, 1893), with 7 plates Delius and Kolle (Z. H. XXIV, 327) (immunity, production of toxins); Grassberger (C. B. XXIII, 25).

Microscopic Appearance.-Very small, short rods, about 0.4 broad, 1.2 μ long, often in pairs, often in sputum within the cells, more rarely united in short threads (68, v). Grassberger observed typical cultures with a marked tendency to form thin and thicker apparent threads, which in part were swollen into spindleform, and at times branching could be seen. This must be studied further.

Spontaneous motion is absent.

Staining Properties.-Somewhat poorly with the ordinary aqueous solutions of anilin dyes, better with alkaline methylene-blue, and best by the application of a very dilute carbol-fuchsin solution for five minutes. With faint staining, the ends are somewhat more deeply stained. Not stained by Gram's method.

Relation to Oxygen.-Obligate aerobe.

Requirements as Regards Nutrient Media and Temperature.-Grows only upon agar smeared with blood (or hemoglobin) or blood-bouillon. Optimum,

37°. Upper limit, 43°; lower, 26°–27°.

Agar Streak.-(Surface smeared with blood.) Clear, like glass, small, hardly confluent, almost structureless colonies.

Bouillon with Addition of Blood.-If the nutrient medium is placed in a thin layer, the Bact. influenzæ develops as delicate, white flocculi.

Special Nutrient Media. According to Grassberger, a mixture of agar and defibrinated blood, heated for one

1 The pseudo-influenza bacilli described by R. Pfeiffer (1. c.) grow as large thick rods and false threads, but are identical with the I. B., according to Grassberger.

hour to 50°-60°, is a specially favorable nutrient medium. According to Grassberger, the influenza bacterium grew with very much greater luxuriance upon unheated bloodmedia in proximity to colonies of the Micr. pyogenes. It may be supposed that heat and the growth of the Micr. pyogenes alter the blood-medium in a similar manner (Z. H. xxv, 453).

Vitality and Duration of Life.-In water, even in the dark, they die in from twenty-eight to thirty-two hours; in agar and bouillon cultures, after two or three weeks. In fresh sputum they are preserved about the same length of time. Rapid drying kills in two hours; slower drying, in from eight to twenty-four hours.

Distribution.-(a) Outside the body: Not found.

(b) In influenza in man: Very abundant in the characteristic, clear, yellowish-green, lumpy, tenacious sputum. They are found purest in the secretion of the finer bronchi ; at first free in clumps, later especially within the pus cells. Also, extensive colonization occurs in the lung tissue, leading to lobular and pseudo-lobular influenza pneumonia. They are often abundant in the nasal secretion in cases of influenza. R. Pfeiffer found them rarely in the blood, and never cultivated them from the blood. In the organs, especially the brain, they are demonstrable relatively seldom (Nauwerck, C. B. xvIII, 395; Pfuhl, Z. H. xxvi, 112). E. Fränkel traced a suppurative meningitis to the I. B. alone (Z. H. xxvII, 315).

Animal Experiments.-Influenza can be transferred to the monkey only, among all the numerous available experimental animals. Devitalized cultures in large quantities are intensely toxic (dyspnea, paralysis) for animals, especially rabbits.

Immunity and Serum Reaction.-Animals which are treated for a long time with I.-toxins do not yield a serum with antitoxic or bactericidal properties, but succumb to infection with a larger quantity of culture (Delius and Kolle).

Special Culture Methods. The bronchial mucus washed in sterile water is triturated somewhat superficially with a little sterile water; and of this, small quantities are smeared over slanted agar and slanted agar smeared with

blood. If the first remain sterile, while delicate, droplike colonies develop upon the second, it speaks in favor of influenza. Bouillon and agar mixed with sterile pigeon blood are highly recommended.

Related Varieties.-The "bacillus of pneumonia in rabbits," cultivated by Beck, R. Pfeiffer's assistant, from rabbits dying spontaneously, is closely related (Beck, Z. H. XV, 363, 1893). Small, fine, non-motile bacilli, twice as long and thick as the influenza bacillus, obligate aerobe, not stained by Gram's method. Does not grow on potato. Upon gelatin it resembles the streptococcus. Upon agar, grayish-yellow, with granular, sharp border, of tough, mucoid consistency. Guinea-pigs, rabbits, and mice are susceptible. Principal changes upon section are pulmonary hyperemia and atelectasis, and fibrinous deposit upon the pleura.

Bacterium ægyptiacum (L. and N.).

Ordinary Name.-Koch-Weeks' bacillus.

Entire literature by Kamen (C. B. xxv, 449), with beautiful photographs.

Microscopically, very small, thin rods (1-2 long); in recent cases are often exceedingly numerous in the secretion

from the eye; sometimes they form short chains. Nonmotile, do not stain by Gram's method. The cultures. resemble in every way those of the influenza bacillus ; their growth is always poor, best upon nutrient media. smeared with blood. Optimum at 37°. They live only a short time-about four days. Scarcely at all pathogenic

for animals.

xerosis group.

Often associated with organisms of the

A differential diagnosis from the Bact. influenzæ appears at present scarcely possible.

It produces in Europe, especially in summer, epidemic conjunctivitis. The disease develops gradually during two or three days; after three or four days the inflammation is more severe, and may be accompanied by abundant purulent secretion. The affection continues severely for a week, and more lightly for two or three weeks.

Frequent in Egypt (Koch), but also observed in England, Paris, Hamburg, Czernowitz, as the cause of epidemics. Never has been observed in Würzburg.

Bacterium tussis convulsivæ (Czaplewski and
Hensel), L. and N.

Literature. Czaplewski and Hensel (Deut. med. Woch., 1897, 586, and C. B. XXII, 641); Koplik (C. B. XXII, 222) and Czaplewski (C. B. XXIV, 865); Zusch (Münch. med. Woch., 1898, 712, and C. B. XXIV, 721 and 769); Vincenzi (C. B. XXIV, 850). (See also Koplik, Johns Hopkins Hospital Bulletin, IX, 79, 1898.—ED.)

Microscopic Appearance.-In smears of the expectorated mucus small short bacilli, often only oval forms, of 0.75 to 1.5 μ in length. Sometimes united in very short chains (68, 1). Koplik describes individuals in old cultures with slightly clubbed ends. In glycerin and sugar-agar there are sometimes longer forms, reminding one of the coryne-bacteria.

Spontaneous motion absent (according to Koplik, present).

Staining Properties. - Tendency to polar staining when dilute staining solutions are employed. Strong staining solutions give the organisms a plumper appear

ance.

Relation to Oxygen.-Facultative anaerobe.

Intensity of Growth.-Usually very modest; often an inoculation from a culture one day old upon the original plate is without result. Growth on agar, poor; better on glycerin-agar; best upon Löffler's serum.

Temperature.-Not below 25°; grows well only in the

incubator.