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the comma may, according to Koch, be prolonged for more than 144 days. It is a question whether the observations of Cunningham are really so much against the comma bacillus as a cause of endemic cholera as that observer appears to think, the life history of the organism is not yet fully worked out, it is known to have more than one form, and it has not yet been studied under all possible conditions.

The observations of Ferd. Hueppe,1 recently published, show that the "commas" when first expelled from the body, having developed under anaerobic conditions, are tender and easily destroyed, but when exposed to air or oxygen they become more resistant and act more energetically. The practical importance of these facts relative to early disinfection is obvious. Hueppe at the same time points out that this difference of vigour in the anaerobic and aerobic condition satisfactorily explains the infrequency of direct infection.

(390) The Bacillus of Finkler and Prior.

A bacillus was discovered by Finkler and Prior in cholera nostra which bears a superficial resemblance to the spirillum of cholera, but it may be readily distinguished by its method of growth in gelatin, the comma bacillus, when inoculated by the stab method shows at the end of twenty-four hours a white track along the course of the stab; on the other hand, under the same conditions, the Finkler-Prior bacillus liquefies the gelatin much quicker, and throughout the whole extent, while the comma only shows a little liquefied well on the top exposed to the air. Hovorka and F. Winkler, by using the albumen of plovers' eggs coagulated at 90° C. and sterilized by exposure to a heat of from 60° to 70° for twenty minutes on three successive days have obtained a culture medium by the aid of which they believe they have a new distinction between the organisms mentioned. A stab culture of Koch's bacillus in this medium soon shows a surrounding layer which reflects light stronger than the rest of the albumen, and hence appears clearer; on observation with a lens are seen greyish

1 Präger med. Wochenschrift, March 19, 1890. Public Health, vol. iii. p. 87. Public Health,

2 Ergänzungshifte zum Central. f. Allgemeine Gesundheitspflege. Bd. I. 1865. 3 Allgemeine Wiener med. Zeitung. XXXIV. Jahr. No. 23.

vol. ii., p. 114.

crowds of colonies, which on the third day occupy the whole breadth of the needle track. There is no real liquefaction although there may be here and there incipient signs of it. The FinklerPrior bacillus shows a liquefaction around the colonies by the second day. This becomes so decided that on the third day the mass of the albumen is detached from the walls of the test tube. By the sixth or seventh day the albumen is coloured yellow -the colour increases in depth until the whole is changed into yellow brown-then the albumen becomes again solid. It is this rapid liquefaction, the yellow colour and subsequent "setting" again of the albumen which forms the distinguishing mark between the two micro-organisms.

(391) The Recognition of the Comma Bacillus by Chemical Tests.

Chemical tests have also been proposed for the recognition of the comma bacillus. Otto Bujwid1 states that when the cholera comma colonies have grown to white points, and beef broth is inoculated with one of them and cultivated for twelve hours at 37° C. the liquid takes a rose colour on the addition of hydrochloric acid. M. J. R. Petrin 2 has also shown that the comma bacillus reduces nitrates to nitrites; but these chemical effects can only be used practically when further research has shown that they are peculiar to this bacillus; in the meantime they must be considered as only confirmatory of the other characters. There is a spirillum (spirillum sputigenum) to be found in saliva and carious teeth, which is morphologically similar to Koch's bacillus, but it is difficult to cultivate, and is apparently a distinct form; there is also another spirillum which is something like Koch's commas which has been isolated from cheese; this spirillum is smaller than the cholera spirillum and has a different method of growth.

(392) Klein's Objections to the " Comma" Theory.

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It remains to be added that Klein has criticized the comma theory, and has also repeated Koch's experiments without confirming them. One of the arguments against Koch's theory, according 1 Zeitschrift f. analytische Chemie, vol. xxvi.; Public Health, vol. i. p. 93. Centralblatt f. Bakteriol in Parasitenkunde. Bd. V. 18; Public Health, vol. ii,

p. 56.

3 Fifteenth Annual Report of the Local Government Board. Supplement, 1886.

to Klein, is that in all infectious diseases produced by a microorganism, the micro-organism is found in the blood or tissues; this no longer holds good, that is if the observations on diphtheria by the French school and by Loeffler are correct; in that disease a micro-organism grows on and within the mucous tissue, is entirely local, and yet affects profoundly the system. Klein views the comma bacillus as accidental, probably being always present in small numbers in the intestines, and then under favouring conditions multiplying; he acknowledges, however, the almost constant presence of the commas in cases of true cholera. Neither the experiments nor the arguments of Klein are sufficiently conclusive, and on the whole the current of scientific opinion leans to the side of Koch.

(393) Experiments on the Communicability of Cholera before the Discovery of the Comma Bacillus.

1. Injections of cholera blood into the veins.

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In 1831 Magendie 1 injected an ounce of cholera blood into the veins of a dog without effect. When eight ounces were employed the dog became affected with cholera-like symptoms and died; the post-mortem appearances had some similitude to those found in cholera. In 1836, a Venetian physician, Dr. Giacinto Namias, and afterwards Semmola,2 inserted blood coagula taken from the hearts of persons dead from cholera, beneath the skin of rabbits; the effects as might be expected were uncertain and contradictory. Marshall,3 in 1849, made seven experiments with cholera blood. He injected the blood into the veins of animals; the effects produced were in every instance considered by the experimenter as sufficiently explained by the assumption that dead blood had been introduced charged "with the products of its own decomposition." A more important experiment was made subsequently by the same observer: blood was taken from six living patients, and after being defibrinated and slightly diluted with water, was injected from 20 to 30 minutes after abstraction into the veins of animals; the quantity injected was from four to six drachms when dogs were employed, and about three drachms for cats and rabbits.

1 Leçons sur le Cholera Morbus, 8vo. Paris, 1837.

2 Annali Universali de Medicina, compilati da A. Omodel, t. 77-78.
3 Brit. and For. Med.-Chir. Rev. vol. xi. 398

Into the veins of two dogs were injected larger quantities of blood taken from patients affected with other diseases to serve as a control. One only of the dogs exhibited any very decided symptoms. This dog was prostrated for many hours, the bowels were slightly relaxed and there was loss of appetite. The following day the animal was well, the other animals suffered very slightly. Injections of fresh living cholera blood by Namias, Carl Schmidt,1 and by Jos. Meyer 2 into the veins of dogs, rabbits, and cats, all gave negative results.

The general result of all the experiments is that although large quantities of blood may produce symptoms, yet that the cause of cholera is not in the blood, or if in the blood cannot affect animals.

II.-Injections of the intestinal discharges of cholera.

Mr. Marshall injected into the jugular veins of cats and dogs filtered rice water discharges. The animals were languid and distressed and had slight purging for two days.

III.-Introduction of the intestinal discharges into the stomach

of animals.

By far the best class of these cases are those of unintentional experiment as when dogs have devoured human cholera vomit or excreta. A well authenticated case is recorded by Meyer. A large house-dog ate portions of his master's cholera stools. 10 hours after, the dog vomited a pale-coloured liquid and discharged a yellowish, offensive, watery dejection. In seven hours he was dead. Hertwig made the post-mortem. A rice-water looking liquid flowed from the mouth, and was contained in large quantity in the alimentary canal. The intestines were congested and the lining membrane covered with white flaky mucous; Peyer's patches were reticulated and surrounded by areola of injection. Von. Hildenbrandt has collected a large number of instances in which domestic animals suffered from a disease resembling cholera in places where cholera was epidemic. Marshall made nine experiments in which vomited or dejected matters were introduced into the stomachs of animals. The experiments were made

1 C. Schmidt, Charakteristik der epidemischen Cholera gegenüber verwandten Transudations-anomalien. Leipzig, 1850, p. 79. 3 Op. cit.

2 Virchows Archiv. f. Pathol. Anat. Bd. iv.

4 Oester. med. Jahrbucher. Bd. xvii., xviii. Vienna, 1838, 1839.

on dogs, cats, guinea-pigs, and rabbits. Two of the three dogs died, one recovered, the symptoms and the post-mortem appearances bore some likeness to cholera.

In 1850 Jos Meyer1 made a similar series of experiments on dogs. Out of six dogs, one only yielded negative results. The five remaining suffered from diarrhea, three died, the post-mortem appearances were not dissimilar from those of cholera.

In 1853 Dr. Lauder Lindsay, then resident physician to the cholera hospital, Edinburgh, induced a fatal diarrhoea among dogs by confining them for a length of time in a small room having a capacity of 1,050 feet, on the floor of which the ejections, excreta, and urine of cholera patients were strewed; the animals were also fed with the blood, urine, and other fluids and solids obtained from the bodies of persons who had died of cholera.

IV. Administration of small quantities of dried excreta.

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Thiersch made a careful series of experiments on white mice. He soaked filter-paper in rice-water cholera discharges, allowed the paper to dry, and fed white mice with paper thus prepared. The experiments were made in several series, the discharges were taken from different parts of the intestine, and allowed to stand and decompose during different periods of time. He found that the mice were not affected by eating filter-paper soaked with the fresh discharges; but that if the discharge was allowed to decompose for from two to six days, it induced a fatal diarrhoea.

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Dr. Burdon Sanderson made a very exact series of similar experiments to those of Thiersch. He found that the rice-water discharges allowed to stand for from three to four days produced a cholera-like disease among mice, and that the disease could be communicated from one affected animal to another of the same species.

It has been the custom of late years to pass by these experiments of Thiersch and Burdon Sanderson, but the results were remarkable, and they deserve repetition aided by bacteriological investigation. There are also reasons to consider the celebrated instance of infection from water described by Macnamara 5 in the

1 Virchows' Archiv. f. Path. Anat. Bd. iv. 31.

Ed. Med. and Surg. Journal. Vol. lxxxi.

3 Haupt Bericht uber die Cholera-Epidemie des Jahres, 1854. Munich, 1857. 4 Ninth Rep. Med. Officer to the Privy Council.

5 Macnamara, A Treatise on Asiatic Cholera, 1870, p. 381

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