Science from an Easy Chair

by Sir E. Ray Lankester

What is this terrible disease which every few years travels from the banks of the Indian Ganges, where it is always present, and makes its way to one or more of the great cities of Europe, killing its thousands with horrifying rapidity? The word “cholera” is used by the great Greek physician of antiquity, Hippocrates, and by his followers down to the days of our own Sydenham, to describe a malady which occurs commonly in summer, is often of severe character, but rarely fatal, and is characterised by the exudation from the walls of the intestine of copious fluid, usually accompanied by vomiting and sometimes by “cramps.” This malady is now distinguished by physicians as “simple cholera,” or European cholera, the last name being misleading, since the disease occurs all over the world. It is caused by a special microbe, which multiplies in the intestines and produces a poison. Other microbes produce similar results. One which causes luminosity in foul salt water has been found to produce cholera-like results when cultivated in a state of purity and swallowed by man. Other poisons besides those produced by microbes set up a sort of “cholera” in animals and man. Drugs of both mineral and vegetable origin have this effect, as every one knows, and are used in small quantities to produce purging. Microbes which are noted for other obvious effects which they produce by the poisons they form in man’s intestines—such as the microbe of typhoid fever—also produce cholera-like purging.

But the name “cholera,” or “the cholera,” is now applied without any further qualification to what would be more correctly described as “Indian cholera,” or “epidemic cholera.” It is a disease which first became known to Europeans in India in 1817, less than a hundred years ago. It resembles “simple” cholera in its general features, but is usually much more violent in its attack, and often causes complete collapse in two or three hours from its onset, and death in as many more. The main point about it is, however, that it is a quickly spreading “epidemic” disease; it invades a whole population, and travels from place to place along definite routes. Although the outbreak of cholera in India in 1817 was the first to attract the attention of Europeans, it was nothing new in India, and was recognised in distant ages by Hindu writers. Its usual name on the delta of the Ganges is “medno-neidan.” Ninety per cent. of the population perished of cholera in some districts of India in 1817, and English troops were attacked by it with terrible results.

Cholera gradually made its way in subsequent years through Persia to Russia, and at last to Western Europe; but it was not until late in the year 1831 that Indian cholera arrived for the first time in England, and in the following year it caused something like a panic. There have been at least three subsequent outbursts of Indian cholera (before that of the year 1908) which have reached Europe, and two of these have reached England and caused profound alarm and anxiety. That in 1854 reached us just before the Crimean War, and caused such rapid and numerous deaths in London, especially in the West End (St. James’s, Westminster), that the corpses were removed in carts as in the days of the plague. It was then that the Broad Street pump became famous, and the carefully demonstrated history of a cesspool leaking into the well of the pump, of the existence of a cholera patient in the house to which the cesspool was attached and of the infection with cholera of healthy people who sent all the way from Hampstead to fetch what they thought was the beautifully pure, cool, and palatable water of Broad Street, St. James’s, caused a most vivid and salutary impression on the public mind. The “water-carriage” of the cholera infection was established as a fact, and the subsequent abolition of surface wells and pumps, as well as of cesspools, in London and other cities was the result. Indeed, the active development of sanitation and sanitary measures of all kinds in Great Britain may be traced to the panic caused by the cholera in 1854 and to the well-founded conviction that it was in the power of the community, by the construction of sewers and the provision of untainted water-supply, to protect itself against such disaster in the future.

Years passed by, and still the actual germ of cholera was unknown. In India it was not even admitted that its diffusion was especially connected with water-supply. The methods of observing with the microscope those minute swarming organisms which are called “bacteria” became immensely improved. They were isolated, cultivated in purity, and the activity of a vast number of different kinds of different shapes, sizes, and modes of growth was ascertained. They were distinguished according to their shape as bacilli, spirilla, micrococci, and so on, and separate kinds were characterised—one producing ordinary putrefaction, another the souring of milk, another the “cheesing” of the same fluid, another the destruction of teeth and of bone, another the terrible anthrax of cattle or wool-sorters’ disease, another (a spiral thread in the blood this!) the recurrent fever of East Europe—each producing its own special poison or other chemical substance.

So it went on till Koch, of Berlin, discovered the bacillus of tubercle and Hansen that of leprosy. Others had failed to find what Koch now found as the result of a special mission on behalf of the German Imperial Government to India (undertaken as nearly as I can recollect about the year 1884)—namely, the living organism ([Fig. 46]) which by its growth in man’s intestine causes Indian cholera. Koch found a spiral threadlike “bacterium” in cholera patients, which readily breaks up into little curved segments like a comma (each less than the one ten-thousandth of an inch in length), and swarms by the million in the intestines of such patients. He showed that it can be cultivated in dilute gelatinised broth, and obtained in spoonfuls. It was, however, only with great difficulty that he could produce cholera in animals by administering this pure concentrated growth of cholera germs to them.

Then a most courageous thing was done. A great and very acute investigator of cholera in Munich, Pettenkofer by name—who did not believe that Koch’s comma-bacillus was really the effective germ of cholera—himself swallowed a whole spoonful—many millions—of the cultivated cholera germ. His assistants did the same—and none of them suffered any ill effect! Few, if any, of the investigators of this question gave up, as a consequence, their conviction that Koch’s bacillus was the real and active cause of cholera. They supposed that it must be necessary for the human intestine to be in a favourable condition—an unhealthy condition—for the Koch’s bacillus to multiply in it. It was by this time known that bacteria of all kinds are exceedingly sensitive in regard to the acidity or alkalinity, the oxygenation or de-oxygenation of the fluids and organic substances in which they can, when exactly suited, multiply with tremendous rapidity. Thus the tubercle bacillus cannot be cultivated on pure blood-serum, but if a trace of glycerine be added to the serum the tubercle bacillus grows, divides, multiplies like yeast in a brewing-vat. A little later Pettenkofer’s audacious experiment was repeated by Dr. Metchnikoff in Paris. He swallowed a cultivated mass of the cholera germ on three successive days, and had no injurious result. Others in his laboratory did the same, with the result of only a slight intestinal disturbance. But of a dozen who thus put the matter to the proof in the Institut Pasteur, one individual acquired an attack of true Indian cholera, accompanied by all the most violent symptoms, which very nearly caused his death. This experiment put an end to all discussion, and demonstrated, once for all, that the comma-bacillus (or spirillum) of Koch is really capable of producing Indian cholera, and is the actual agent of this disease.

Fig. 46.—a, b, c, d. The cholera spirillum, or comma-bacillus of Koch; a, spirillum stage of growth, with vibrating flagellum, by which it is driven along with screw-like movement; b, the spirillum has lost its flagellum, and is motionless: it is marked off into separate segments; c, the segments have separated from one another as comma-shaped pieces, hence the name “comma-bacillus” given to it by Koch; d, a number of comma-bacilli of cholera which have developed tails of vibratile protoplasm (like a single cilium), and are swimming about, being driven by the lashing of these tails; e, a cubical packet of sarcina; f, a double row of the spherical units (cocci or micrococci), which form a sarcina-packet; g, similar cocci separated.