THE interest excited in cholera by its presence in Europe during last summer and autumn was reawakened in the spring by the prospect of a war which might have brought us face to face with an enemy much more formidable than the armies of Russia. War is no longer in immediate prospect, so that for the present we need not think of cholera in connection with Asia Minor or the Black Sea. But the epidemic which is now raging with such pitiless fury in the Mediterranean provinces of Spain makes us all feel that the threat of 1884 may be fulfilled in 1885. There is probably no serious ground for apprehending that we shall have to do with cholera in England this year; the chance, however, is sufficiently near to make it reasonable to

The substance of a lecture delivered at the Royal Institution on Friday evening, May 15, 1885.

NEW SERIES.-VOL. XLII., No. 4

inquire whether any useful information as to the causes of cholera, or the way in which it can best be guarded against, has been gained since the last time that the disease visited our shores.

In dealing with cholera, as in other matters in respect of which conduct must be guided by knowledge of some kind, the question what sort of knowledge is best and most valuable comes prominently to the front, and is one on which those who profess to follow the scientific method, and those who profess to be guided by what they are pleased to call common sense, are apt to entertain different opinions. The question is in reality not between two kinds of knowledge, but between two ways of acquiring the same kind of knowledge. Those of us who have studied cholera at home in the hospital ward or in the laboratory approach the subject on one side.

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Those whose lives, like that of my friend Dr. J. M. Cuningham, the Sanitary Commissioner with the Government of India, have for the most part been spent in a prolonged encounter with cholera year after year, as it presents itself in prisons and armies and among the multitudinous populations of our Indian Empire, from another. But we are all seeking the same kind of knowledge, and what is more, we all tend to the same conclusions. If, for example, a comparison be made of the recent work published by Dr. Cuningham, "Cholera: What can the State do to prevent it?" in which he professes to confine himself to considerations of common sense and deprecates the interference of science with practical questions, with the lecture given a few months ago to the people of Munich by Professor von Pettenkofer, who is acknowledged to be one of the highest scientific authorities on the etiology of cholera, it will be found that the German Gelehrter and the English administrator say practically the same thing.

As this paper is intended for the perusal of persons who do not specially concern themselves with pathology, I will enter as little as possible upon subjects of controversy, regarding it as of much more importance that those notions as to the cause and nature of cholera, about which there is no dispute, should be generally understood, than that the claims of rival investigators should be vindicated. In the slow process by which new knowledge is acquired, strife is a necessary and unquestionably a productive element. Burning questions arise wherever and whenever scientific investigation bears, or appears to bear, on practical action. Eventually they find their solution; but in the mean time it is almost impossible for those who are immediately concerned in discussing them to guard against the influence of personal antagonisms and predilections. As regards all recent questions of this kind, I think that I am myself in a position to look at them from a distance, for I have had no direct concern with cholera since 1866. I will therefore ask the reader to regard me neither as a contagionist nor as a localist, and to dismiss the commabacillus " from his mind until we have

had time to take a general view of the tendencies which this great world plague has manifested in its dealings with mankind since it first found its way into Europe.

It is agreed by all authorities that cholera is native in India, and particularly in the district where it is now endemic'' namely, in the district which corresponds roughly to the deltas of the Ganges and Brahmaputra and the district of Cuttack. As, however, it for the most part confined its ravages to the native populations, with whom at that time our relations were much less direct and intimate than they are now, it excited no general interest, and was indeed so little known to medical men that when in 1817 the disease broke out at Jessore, near Calcutta, it was believed to be an entirely new malady. Even now there are some writers who speak of Jessore as the "cradle of cholera" and the year 1817 as the starting-point of its history, notwithstanding that the inquiries which were then initiated showed not only that in Bengal the disease was an annual visitor, but that in Calcutta itself it was fatally prevalent in the native town several weeks before Dr. Tytler was called to see the first case at Jessore.

The great epidemic of 1817 and 1818 was distinguished from previous ones by its extent and destructiveness, but chiefly by the circumstance that in this year it became for the first time a serious obstacle to English conquest. How or when it began it is probably impossible to determine, for evidence exists of its presence in July 1817 within a few weeks at places so distant from one another as Patna and Dacca. Two months later it was at Benares, Allahabad, and Mirzapore; and in October of the same year an event occurred which at once gave the disease a significance it had not be fore possessed. The Marquis of Hastings, with an army of over ten thousand Europeans and a much larger native force, was in the Bundelcund, not far from Allahabad, where cholera was then raging. Cholera had on several previous occasions interfered with military operations, but this time it attacked Hastings' European troops with a violence of which there had before been no example. The pestilence continued for

several weeks with unabated destructiveness, until early in November the army was withdrawn from the Bundelcund and moved westwards in its march tow ards Gwalior, on which the mortality at once subsided. Thousands of dead and dying were left behind, but cholera was left behind with them, and a lesson was learned which has since been often repeated in Indian experience that when a military force is encountered by cholera, removal from the infected locality is the only effectual way of checking it.

In 1818 cholera overspread the whole Indian Peninsula. Westward it extended up the Ganges valley to Delhi and Agra, and eventually found its way across the Sutlej to Lahore. Southwards it flanked the line of the Vindhya, attacked Nagpore, and thence spread to other places in Central India. Along the east coast there were destructive epidemics at Vizagapatam, in the deltas of the Godavery and Kistnah, at Madras and Pondicherry, and various other places further south. In 1819 Ceylon, which had been similarly invaded in 1804 and probably often previously, suffered very severely. The spread of cholera in the island was naturally enough attributed to the commercial intercourse between Trincomalee and the infected ports on the coast of Coromandel. Whatever may be said for or against this belief as regards Ceylon, it is difficult to offer any other explanation of the outbreak which occurred the same year in Mauritius than the obvious one that it was carried over the sea by trading ships, for even though the evidence which exists that the Mauritius epidemic took its start from the arrival, with cholera on board, of the ship Topaze, were proved to be defective, it could scarcely be accounted for in any other way than as a result of commercial intercourse. From Mauritius chol. ra spread to Madagascar and the Portuguese settlements on the east coast of Africa.

In the course of 1820 cholera seems to have spread over Asia. In that year it was at Canton and Nankin, and travelled up the Yang-tse-kiang into the interior of China, and finally reached the capital. In the same year it is said that 150,000 persons died of it in the island of Java. Celebes, the Moluccas, and

the Philippines were invaded at the same time. Burmah, Siam, and Singapore had been ravaged the previous year, and it was believed that the latter place, where so many streams of commercial movement meet, was the source whence the infection was distributed over China and the Malay Archipelago. The explanation was probably correct. By the universal infection of all the ports of our Indian dependencies in 1819 the channels of European commerce in the East were more thoroughly contaminated than they had ever been before. Modern experience teaches us that though cholera is very unapt to spread in this way, it may do so; and I confess it appears to me quite impossible to doubt that in those early years of its history it did so.

From 1820 onwards we have evidence that cholera has never been absent from Bengal, and has behaved throughout in the same way that it does now. The best general idea of the extent of its influence and of the differences which subsist between years of great epidemic prevalence and others, may be gained by an examination of the series of maps which have been published by the Indian Government. The conclusions which these maps suggest, and which are confirmed by the more minute and exhaustive study of cholera statistics which has been made by Dr. Bryden,* may be summarily stated as follows.

Within certain areas, the limits of which comprise the alluvial plains adjoining great rivers, and particularly in the deltas of such rivers, cholera is always present. Outside these so-called endemic areas some places are distinguished by their liability to the epidemic prevalence of the disease, others by their special immunity, and in general no relation can be traced between liability to epidemic prevalence and personal intercourse with infected districts; so that, however clear it may be that the infection of cholera is capable, under certain conditions, of being conveyed from place to place, Indian experience affords no ground for attributing any importance to such conveyance as a means of the spread of cholera in that country.

* See "Epidemic Cholera in the Bengal Presidency. By James L. Bryden, M.D. Calcutta. 1869.

Let me now try to give an account of the circumstances which led to the escape of cholera, if such an expression may be used, from its Indian home into Europe. As probably every reader knows, the first European country invaded by cholera was Russia, and the first European town of any importance was Orenburg, on the Ural, one of the great feeders of the Caspian. How did cholera find its way from the Indian Peninsula to the Caspian? The only answer that can be given is that the communication took place by way of Persia, and that Persia itself was invaded, not, as has been sometimes said, by Afghanistan, but by the Persian Gulf. In 1821-that is, a year after the epidemic of Zanzibar-there was a destructive outbreak of cholera at Muscat in Arabia and at the Persian port of Bushire, and a little later at Bagdad. From these littoral beginnings the epidemic spread during the next year (1822) over the whole of Persia and great part of Asia Minor. In 1823 it was in Damascus and Aleppo, having at the same time or previously existed in Iskanderoon and other places on the Mediterranean. It is usually stated that in 1822 cholera crossed the Caucasus for the first time, the only ground for the statement being that in that year it prevailed at about the same time at Tiflis and at Astrachan. In reality, cholera seems to have reached Astrachan, not over the Caucasus, but by creeping along the Caspian shores from Resht, which was the first place invaded. In the Caspian, as in India, it found a suitable soil in the deltas of the Terek and the Volga, and finally ascended the Ural, as has been already noted, to Orenburg. Beyond these limits cholera failed to penetrate further into Europe either by the Mediterranean, the Black Sea, or the Caspian, its disappearance in Syria and in Astrachan being simultaneous. There seems good reason for believing that it was entirely absent for six years (1823 to 1829), but in August 1829 it reappeared in Orenburg without its being possible to ascertain with any certainty whence it came. All that can be asserted is, that it was at the same time widely scattered over Central Asia, in Afghanistan, at Teheran, at Khiva and Bokhara, as well as on the shores of the Caspian,

and that in consequence it was on this occasion believed to have rather come by Central Asia than from Persia.

In 1830, the year after the Orenburg epidemic, cholera made its first great advance into Europe. In August of that year there were destructive epidemics at Astrachan (where there is good reason for believing that the cholera had wintered), at Zaritzin, at Saratov, at Kasan, and finally at Penza-all, with the exception of the last, on the Volga. A few weeks later it was at Taganrog, Kertch, Sebastopol, Cherson and Odessa, and finally, in September 1830, began the epidemic of Moscow, which was rendered memorable by the self-sacrifice and devotion of the Russian Emperor. In 1831 cholera for the first time spread over Central Europe. Beyond the broad fact that Russia was first invaded, it is quite impossible to say how this momentous result was brought about, as the reader may at once satisfy himself by comparing the following dates, which are derived from Dr. Peters' History of the Travels of Asiatic Cholera," published in the Reports of the United States War Department:-Moscow, September 1830 to March 1831; and in the latter year, Petersburg, June; Warsaw and Cracow, April; Dantzic, March; Berlin, August; Hamburg, October. In October 1831 cholera appeared at Sunderland and became epidemic there and in the neighboring towns, Newcastle, Gateshead, Shields; but it was not until a large number of persons had been attacked and died that it was admitted to be Asiatic. There is evidence that during the preceding summer the disease had been introduced into the port of London, and had even spread among the maritime population; but notwithstanding that no special precautions appear to have been taken, London itself remained exempt until early in the spring of 1832.

In the summer of that year it prevailed in most of the seaport towns of England and Ireland, and was carried across the Atlantic by Irish emigrants. For when, in June 1832, the disease broke out in a lodging-house in Quebec* which had received a number of these

* Dr. Peters, loc. cit. p. 564.

emigrants, destroyed fifty-six lives, and in the next fortnight spread everywhere in the town, it is impossible to doubt that these persons brought with them to their new homes the seeds of cholera. The history of the invasion of Montreal, which occurred about simultaneously, was but a repetition of the experience of Quebec. During the autumn of 1832 and the year following, cholera ascended the St. Lawrence to Chicago, and thence found its way to the Upper Mississippi, where it very seriously interfered with the military operations against the Indians. In 1833 it appeared in Cuba, whence it spread later in the same year to Mobile, New Orleans, Tampico, and other ports on the Gulf of Mexico, and eventually to Mexico and Vera Cruz. Epidemics continued to occur in the Spanish-speaking countries of the New World until 1834-35, in the former of which years Spain itself was for the first time invaded. The great epidemics of Madrid and Barcelona were followed by a general extension along the Mediterranean coast-Cette, Marseilles, Toulon, Nice, Genoa, and Naples being attacked in the order in which they have been mentioned. As there was an interval between the Mediterranean spread and the great wave which had affected England in 1832, it seemed as if the disease, which was communicated to the New World from the Old, had been returned back to it from the West Indies. Whether this was so or not is scarcely worth inquiry. It would be much more interesting if we could explain how it was that the Mediterranean, which was in 1832 exposed to every conceivable chance of infection, was not invaded until 1834; and why, having seized upon such ports as Marseilles and Genoa, it showed no tendency to travel northwards to the country it had previously invaded. me add that cholera did not leave Europe until 1837, after which the Western World was free from it for a decade.

Cholera reached the Caspian for the third time in April 1847, its arrival being the outcome of a general spread of the disease in Persia and Central Asia. It soon found its way into the interior of Russia and broke out for the second time in Moscow, two months after it had appeared, almost simultaneously, at

Astrachan and Constantinople. By the winter of 1847-8 it was at Riga, and spread, during the following summer, just as it had done before, along the Baltic coast, reaching Hamburg in September.

The conveyance of cholera into England, and from England to America, was but a repetition of what had happened in 1832; and the same sort of evidence existed at New Orleans and at New York, in which places the epidemic began simultaneously (December 1848) of importation by emigrants. From 1847 Western Europe was again free from cholera for six years, notwithstanding that it was always present somewhere in the East. 1853 was a cholera year : it was marked by a fearful epidemic in St. Petersburg, which again spread along the Baltic coast, reaching London and Liverpool in July, but not becoming epidemic until the following year.

After a dozen years of immunity, cholera again appeared in Europe in 1865.

On this occasion it was generally believed that the pestilence reached Europe, not as before by the Caspian and Black Sea, but by the Mediterranean. There is no doubt that cholera was rife at Jedda and Mecca in the spring of 1865, also that it prevailed from the beginning of June in Alexandria, and appeared in Malta on the 20th of that month, and about the same time at Marseilles, and subsequently on the coast of Spain (Valencia). As was the case last summer, the seed was conveyed to Paris, and on that occasion bore fruit in the deaths of about 7,000 persons in five months. There was also, as many readers will remember, a small epidemic at Southampton, the origin of which was traced by Dr. Parkes to the arrival of ships with cholera on board from Alexandria; but with this exception Western Europe remained free until the following year. Nor in all probability would England have ever suffered as it did in 1866, had the sporadic spread of cholera from the Mecca pilgrims been our only risk. At the time that all these events were going on about the Mediterranean a new storm was brewing in the old quarter-in North Germany. The appearance of cholera on August 29, 1865, at Altenburg, a place situated in the very middle of Germany, was one of