spinal ganglia of human beings or animals dead of rabies, by Mann's methylene-blue and eosin method, it was possible to demonstrate in the interior of the nerve-cells of their protoplasmic process red colored, rounded bodies, measuring 4 to 10 μ, as a rule, though varying from 1 to 25 μ. In experimental infections under the dura they were most num Fig. 133.-Negri bodies. Cells from Ammon's horn impression of Cow 133, dried and fixed with gentle heat and stained with saturated alcoholic eosin and Löffler's alkaline methylene-blue. Drawn with onetwelfth oil immersion. Oc. 3 (Frothingham). erous in the hippocampal convolution. These bodies have now become known as Negri bodies. The careful studies of Williams and Lowden* convince them that the Negri bodies are protozoan organisms and that their presence is pathognomonic of rabies. At the State Live-stock Sanitary Board of Pennsylvania, Reichel and Englet stain Negri bodies with the following: * "Jour. Infectious Diseases," III, 452, 1906. † Personal communication. Sat. alc. sol. methylene violet... Sat. alc. sol. fuchsin... IO C.C. 7 drops 40 c.c. The smears of cerebellum or hippocampus are fixed with absolute alcohol and ether and the stain poured on, heated, poured back into the bottle, again poured on, heated and poured back into the bottle, this being done three times, each time for about half a minute. Then wash in water, blot, and examine. To examine, a nerve-cell is found with the low power and then examined with the high power, The Negri bodies are brick red. The stain soon fades. Smears kept for any length of time lose the staining reaction. Antirabic Serum.-Babes and Lepp* thought that the serum of animals that have received repeated injections of the crushed nervous tissue of rabid animals was neutralizing or destructive to the rabies virus in vitro, called it “antirabic serum," and believed that it conferred a defensive power upon other animals. Mariet found it to be a simple neurotoxic serum and inert in its action upon the virus. *"Ann. de l'Inst. Pasteur," 1889, III. "Compt.-rendu Soc. Biol.," t. LVI, June 18, 1904, p. 1030. CHAPTER VI. CEREBROSPINAL MENINGITIS. DIPLOCOCCUS INTRACELLULARIS MENINGITIDIS General Characteristics.-A minute non-motile, non-flagellate, non-sporogenous, non-chromogenic, non-liquefying, aërobic and optionally anaërobic, pathogenic coccus, staining by ordinary methods, but not by Gram's method. Acute cerebrospinal meningitis may be secondary to various more or less well-localized infections when it depends upon such micro-organisms as may be carried by accident to the meninges. Among these may be mentioned pneumococci, staphylococci, streptococci, Bacillus influenzæ, B. typhosus, B. coli, B. mallei, B. pestis, and others. In addition to these cases, however, there are numerous cases of primary infection of the membranes, either sporadic or epidemic in occurrence. Such constitute the disease known as cerebrospinal fever, epidemic cerebrospinal meningitis, or spotted fever." It is a very dangerous febrile malady, characterized by high temperature, an irregular exanthem, early meningitis, a moderate degree of contagion, and a high mortality. The cause of this infection is a specific organism known as the meningococcus, or Diplococcus intracellularis meningitidis. As early as 1887 Weichselbaum* carefully described a diplococcus found in 6 cases of cerebrospinal meningitis that may have been identical with one found by Leichtensternt in 1885 in the purulent exudate of a case of meningitis, and with a coccus observed as early as 1884 by Celli and Marchiafava. Weichselbaum's studies and description of this coccus seem to have attracted but little attention at first, and references to them are but brief in most of the text books. The prevailing opinion was that its occurrence in * "Fortschritte der Med.," x, 18 and 19. cerebrospinal meningitis was accidental, as inoculations into animals showed its pathogenic power to be very limited. The careful studies of Jäger,* Scherer, † Councilman, and Mallory and Wright (embracing 55 cases, in which the cocci were found by culture or by microscopic examination in 38), and of Flatten, § Schneider, § Rieger, § Schmidt, § Göppert, § Flügge, § von Lingelsheim, § and others. Besredka and Flexner** have, however, shown the diplococcus of Weichselbaum to be, without doubt, the specific organism. Fig. 134.—Meningococcus in spinal fluid (from Hiss and Zinsser, 'Text-Book of Bacteriology," D. Appleton & Co., Publishers). 64 Distribution. The distribution of Diplococcus intracellularis in nature is as yet unknown. It has been found in cerebrospinal meningitis by those who have looked for it, twice has been found in the nose in coryza by Scherer, has been found in the conjunctiva by Carl Frankel†† and Axenfeld, ‡‡ and in the purulent discharges of rhinitis and otitis by Jager. §§ Morphology. The micro-organism is a biscuit-shaped diplococcus having a great resemblance to the gonococcus. * "Zeitschrift für Hygiene," XIX, 2, 351. "Centralbl. f. Bakt. u. Parasitenk.," 1895, XVII, 13 and 14. $"Klinisches Jahrbuch," 1906. "Annales de l'Inst. Pasteur," 1906, xx, 4. **"Jour. Exp. Med.," 1906–07. tt "Zeitschrift für Hygiene," June 14, 1899. Lubarsch and Oestertag, "Ergebnisse der allg. Path. u. path. Anat.," III, S. 573. §§ "Deutsche med. Wochenschrift," 1894, S. 407. This resemblance is further increased by the fact that the cocci are usually found inclosed in the protoplasm of the leukocytes. Weichselbaum, by whom this was first observed, found it constant in sections of the brain and its membranes, though in the exudate of the disease a good many free cocci may be observed. It was this peculiar relationship to the cells that led Weichselbaum to name the organism Diplococcus intracellularis. Many of the cocci inclosed in the cells are apparently dead and degenerated, as they stain badly and do not grow when the pus is transferred to culture-media. Identification. Carl Fränkel, in discussing the microorganism, points out that its morphologic peculiarities have much in common with the pneumococcus, so that the most refined methods of differentiation should always precede a positive determination. Its resemblance to the gonococcus should also be kept in mind. Perhaps the greatest difficulty obtains in making a certain differentiation between the meningococcus and Micrococcus catarrhalis (q. v.), especially when such investigations are intended as discovering the former organism in the nasal discharges. This cannot be done by microscopic examination, but must be achieved through cultivation of the organisms and observation of the cultures. Micrococcus catarrhalis grows well upon nearly all culture-media; meningococci, very sparsely except upon special media. The former organism grows fairly well at room temperatures (20° C. or less); the latter, only at 25° C. and above. The colonies of the former are coarsely granular; those of the latter, finely granular. Staining. The organism is easily stained with the usual aqueous solutions of the anilin dyes. According to Weichselbaum, Mallory, and Wright it does not stain by Gram's method. For staining the meningococcus the method of Pick and Jacobsohn* is highly praised by Carl Frankel, who modifies it by adding three times as much carbol-fuchsin as is recommended in the original instructions, which are as follows: Mix 20 c.c. of water with 8 drops of saturated methylene-blue solution; then add 45 to 50 drops of carbol-fuchsin. Allow the fluid to act upon the cover-glass for five minutes. cocci alone are blue, all else red. *"Berliner klin. Wochenschrift," 1896, S. 811. The |