disease is easily produced in rabbits by inoculation with the perfectly clear and apparently entirely sterile serum from other cases. Also dogs and men react to the inoculation (C. B. xx111, 865).

Noma.

Petruschky has found diphtheria bacteria together with pseudodiphtheria bacteria in two cases of noma faciei, which he cured with diphtheria antitoxin (Deut. med. Wochenschr., 1898, 600).

Epidemic Parotitis.

Laveran (Compt. rend. de la soc. de Biolog., 1893, 95) found diplococci in the blood and organs in 67 out of 92 cases of mumps. They kill mice and cause in rabbits and dogs a transitory orchitis, which often is associated with mumps also. Mecray and Walsh (C. B. xxi, 68) have made similar observations. The cultures were described by the latter authors as very similar to those of very poorly growing Microc. pyogenes.

Diseases of Plants.

In spite of the efforts of numerous investigators to demonstrate bacteria as the cause of diseases of plants, we possess little knowledge which is free from objection in this field. The botanist Alfred Fischer takes an especially skeptical stand regarding the statements so far made (C. B. L. v, 279), while Erwin Smith, who has himself done much work in this field, is much more optimistic in his judgment, and considers the connection of bacteria and disease to have been demonstrated in a whole series of instances. He enumerates some of the varieties of bacteria which are most certainly pathogenic for plants (C. B. L. v, 271; in the same place the literature is given). We refer to the following: Bacillus amylovorus Burrill (cause of a disease of apple and pear trees), Bacillus oleæ Savastano (tuberculosis of the olive tree), Bacillus hyacinthisepticus Heinz, Bacillus tracheiphilus Erw. Smith (injurious to various cucurbitaceae), Bacillus solanacearum

Erw. Smith (injurious to crucifera). Besides, there have been described bacterial diseases of vines, celery, and sugar-beets, yet only exceptionally are the descriptions sufficiently complete.

Rachitis.

Mircoli ascribes it to Microc. and Strept. pyogenes (C. B. xx, 321).

Acute Rheumatism.

It may be mentioned that Sawtschenko, with Achalme, has recently recognized the cause of acute rheumatism in an anaerobic, sporulating bacillus. Confirmation is awaited with interest (C. B. XXIV, 794).

Cattle Plague.

We only know that the causative agent does not pass through a clay filter: the German investigators in South Africa consider the statements, accompanied by illustrations, of Nencki, Sieber, and Wyznikiewicz (C. B. xxïï, 529) as delusions. They recognize the cause of the plague in a small, spherical organism, but do not directly designate it a micrococcus. The organism is said to grow in peptone solution.

According to Abbe, the limit of the working capacity of our microscopes lies at 0.1 to 0.2 μ.

Scarlatina.

Many of the older writers especially, and of the newer ones, for example, d'Espine (C. B. XVIII, 132),—are of the opinion that the specific cause of scarlatina resides in the streptococcus which is very frequently present, but this is almost certainly not true. Czajkowski (C. B. XVIII, 116) never failed to find in the blood of seventeen cases of scarlatina a diplococcus (according to the illustrations, more like short diplobacilli) which grows to a limited extent upon solid nutrient media (glycerin-agar, blood-agar, serum), more luxuriantly in fluid nutrient media, and is pathogenic for mice. It is not stated whether the diplococcus appears as a streptococcus upon

fluid nutrient media. The great tenacity of the cultures is striking.

Doehle (C. B. XII, 906) and L. Pfeiffer consider protozoa to be the cause of scarlatina.

Ulcerative Stomatitis and Angina.

Bernheim (C. B. XXIH, 177) described two organisms as frequently or constantly present in the ulcers of the gums and tonsils:

1. A bacillus resembling the B. diphtheria (once noticed to be motile), somewhat larger than it, with pointed ends, often more or less curved, staining rather faintly with Löffler's methylene-blue, and decolorized by Gram's method if the alcohol acts a long time.

2. A fine spirochete, which does not stain by Gram's method, similar to the spirochætæ of the teeth.

Neither could be cultivated.

Similar results have been obtained by many other writers, as Vincent and Abel. (See Abel, C. B. xxiv, 1). The results obtained by Vincent in hospital gangrene in Madagascar are strikingly similar; also both organisms were present. (Compare p. 468.)

J. Seitz has described as the Bacillus hastilis a widely distributed (tonsils, etc.), long, slender organism with pointed ends, which has not been obtained in pure culture. It appears to be closely related to Bernheim's organism of stomatitis ulcerosa. From non-saccharine bouillon it forms foul-smelling gas (Z. H. xxx, 47).

Trichorrhexis Nodosa.

According to Marcusfeld, caused by a sporulating bacillus, perhaps from the subtilis group. The relation to the disease is uncertain (C. B. xxi, 230).

Typhus Exanthematicus.

Lewaschoff (C. B. XII, 635, 728; xvi, p. 132) claims to have cultivated a characteristic Micrococcus exanthematicus in pure culture upon ascites-agar from the juice of the spleen or blood from the finger in 118 cases of typhus

fever. It is strikingly motile, always in the blood, and grows anaerobically. Both in the blood and in cultures many, but not all, of the individuals present one or two very long, motile, spiral appendages, which take the stain for flagella. Lewaschoff calls this form of remarkable spirochete, exanthematica. According to his opinion, there is perfect agreement between his findings and the newer investigations of Ljubimoff (cocci), Calmette and Thoinot (A. P., 1892, 39) (egg-shaped bodies and spirilla), von Dubief and Bruhl (C. B. xiv, 17), Curtis, and Combemale (diplococci).

APPENDIX IV.

Essentials of Bacteriologic Technic.

The following directions and short explanations include about all the technical material which is given in a thorough bacteriologic course. We have introduced only those things which are essential and, according to our experience, practical, without referring to the literature. More details will be found in the books mentioned in the preface.

I. Microscopic Examination of Bacteria.

1. Hints upon Microscopic Technic.

For bacteriologic examination we use almost exclusively the modern microscope with Abbé's illuminating apparatus, iris diaphragm, and a low-power and an oil-immersion objective.

(A) Low magnification (60 to 100 times) with a narrow diaphragm is used in the minute examination of plate cultures. In this examination either the cover 1 is removed and the colony examined from above, or, if one does not wish to contaminate the plate by exposing it, the dish is laid upon the cover and the colony examined from below, but this does not give such characteristic pictures in all cases. (B) High Magnification. Oil-immersion Objective (700 to 1200 times).-This finds its use in the examination of single individuals. A drop of cedar oil is placed upon the preparation (slide, cover-glass) and the tube is lowered by means of the coarse adjust1 Our plate cultures are always poured into dishes.

ment until the lens just touches the oil; then it is accurately adjusted upon the preparation with the micrometer screw.

(a) Unstained preparations. Narrow diaphragm! They are examined in two ways:

1. A drop of pure culture in a fluid medium or a little drop of water with a trace of pure culture mixed in it is placed between the slide and cover-glass; or, better,

2. In a hanging drop. A drop of a pure culture in a fluid medium or a drop of bouillon in which is mixed a minute quantity of a pure culture is placed upon a cover-glass; the cover-glass is then turned over and placed upon a hollow ground slide so that the drop is suspended within the hollow. The cover-glass is now fixed to the slide by applying a very little water to each corner of the cover, or, if the observation is to be more prolonged, by means of vaselin.

(b) Stained preparations. Open diaphragm! Abbé's illuminating apparatus. In the examination of sections with a double stain, the wide diaphragm is required for the bacteria, the narrow opening for the tissues.

(C) Cleaning the Preparations and the Microscope.-The immersion oil is always gently brushed off, and now and then quickly cleaned with xylol and chamois skin; the setting of the lens is loosened by prolonged action of the xylol. Also immersion oil dried upon the cover-glasses of old preparations is readily removed by xylol.

2. The most Important Solutions for Use in Making Preparations.

(A) Staining Solutions.

1. Aqueous Alcoholic Solutions of Fuchsin and Methyleneblue.-A concentrated "stock-solution" is prepared by pouring absolute alcohol upon the pulverized dyes (fuchsin, methylene-blue) in bottles, and after shaking and allowing them to stand a few hours, they are filtered. Of this saturated solution 1 part is mixed with 4 parts of distilled water, and before using is filtered. In order to obtain good preparations it is better to stain a longer time with weaker solutions than for a short time with strong solutions. 2. Carbol-fuchsin (Ziehl's Solution).—

3. Anilin Fuchsin.-Four parts of anilin oil (anilin. pur.) are well shaken several minutes with 100 parts of distilled water, and then filtered until all the water has passed through clear (then the funnel is removed, since otherwise oil will also pass through). In this anilin water 4.0 gm. fuchsin are dissolved and it is again filtered.

4. Anilin Gentian-violet (Ehrlich's Solution).-To 100 c.c. of anilin water, 11 c.c. of a concentrated alcoholic solution of gentianviolet (stock solution) is added. This solution does not keep long.