the blessed Nativity, which we celebrate in December. Prudent matrons calculating after this rule, as long as they note the day of the month in which the catamenia usually disappear, are rarely out of their reckoning; but after ten lunar months have elapsed, fall into labour and reap the fruit of their womb the very day on which the catamenia would have appeared had impregnation not taken place."

It remains for us to say of Dr. Duncan's very able work that it is scarcely possible to do justice to it in a review. It is too profound for summary judgment. To every one who studies midwifery scientifically it is essential; and to those who deal with one of the most important social problems of the day, viz., that of the laws of population, its perusal will afford both profit and instruction.

VI.-Cholera, its Origin and Distribution.1

THERE is too much reason to fear that in the course of the

11. Asiatic Cholera in Bristol in 1866. By WILLIAM BUDD, M.D., F.R.S. Bristol, 1871.

2. Seventh Annual Report of the Sanitary Commissioner with the Government of India, 1871. Calcutta.

3. Second Annual Report of the Sanitary Commissioners for the Central Provinces. Nagpur, 1870.

4. Cholera in Southern India: a Record of the Progress of Cholera in 1870. By Surgeon W. R. CORNISH, Sanitary Commissioner for Madras. Madras. 1871. 5. Report on the General Aspects of Epidemic Cholera in 1869: a Sequel to a Report on the Cholera of 1866-68. By JAMES L. BRYDEN, M.D., Statistical Officer attached to the Sanitary Commissioners with the Government of India. Calcutta, 1870.

6. Note on the Epidemic Connection of the Cholera of Madras and Bombay with the Cholera Epidemics of the Bengal Presidency. By JAMES L. BRYDEN, M.D. Calcutta, 1871.

7. Report on Measures adopted for Sanitary Improvements in India, from June, 1870, to June, 1871. Printed by Order of the Secretary of State for India in Council. London, 1871.

8. Hindu View of Cholera. By GOLAUB SING, M.D. London, 1871.

9. Mode d'Invasion et de Propagation du Choléra étudié à Smyrna. Par le Dr. CHASSEAUD. Constantinople, 1871.

10. Epidemic Cholera, in Reynolds's System of Medicine. Vol. I. By Dr. GOODEVE.

11. Report on the Cause and Mode of Diffusion of Epidemic Cholera. By WM. BALY, M.D. London, 1854.

12. A Treatise on Asiatic Cholera. By C. MACNAMARA. London and Calcutta, 1870.

13. Etude Sommaire sur l'Importation du Choléra, et les moyens de le prévenir. Par le Dr. SIRUS PIRONDI et le Dr. AUGUSTIN FABRE. Marseilles, 1865.

14. Ninth Report of the Medical Officer of the Privy Council. London, 1867. 15. On the Mode of Communication of Cholera. By JOHN SNOW, M.D. London, 1855.

present year cholera may reach our shores and prevail once more as an epidemic pestilence.

The possibility of such a visitation renders it desirable to review the evidence which we possess as to the manner in which this formidable malady originates and spreads.

The men who have contributed most to our knowledge of the origin and propagation of cholera have been those who, laying a firm hold upon certain unquestionable facts, have perseveringly applied them in explanation of the phenomena of the disease. Amongst these Dr. William Budd and the late Dr. Snow deserve honorable mention. Dr. Snow was the first to direct attention to the influence of impure water as a means by which the disease is communicated, and by his persevering efforts, in the face of ridicule, opposition, and sceptical criticism, he compelled attention to this most important subject. His error consisted in the adoption of a too exclusive theory. He maintained that the essential cause of cholera is the swallowing of the specific discharges which have been expelled by a previous sufferer from the disease. He believed that the poisonous secretions, being swallowed either with food or drink, but most commonly with contaminated water, are thus brought into contact with the mucous membrane of the alimentary canal, where they undergo a rapid increase, and give rise to the phenomena of the disease (15, p. 1).1 Now, it is certain that cholera not unfrequently originates under circumstances which forbid us to assume that either the food or the drink has been the vehicle of the poison. We believe with Dr. William Budd that the poison of cholera is cast off with the characteristic discharges from the alimentary canal, and that the disease is communicated to others in the following principal ways:-1. By the soiled hands of the attendants, who are not careful to wash before taking their food. 2. By means of bed and body linen, carpets, and other articles, soiled by the choleraic discharges. 3. The discharges, finding their way into the sewers and into the soil, may spread the disease in various ways-(a) by percolating through the soil into wells and other reservoirs of drinking water; (b) by rising with watery vapour into the air; (c) by becoming dried, and then dispersed with the atmosphere in form of an impalpable dust. In the words of Mr. Simon, "it cannot be too distinctly understood that the person who contracts cholera in this country is, ipso facto, demonstrated with almost absolute certainty to have been exposed to excre

We have numbered the various publications which we shall have to quote in the course of this article, and to prevent the necessity of repeating the titles of the works we shall refer to them by giving the numbers corresponding with those at p. 56.

mental pollution-excrement-sodden earth, excrement-reeking air, excrement-tainted water; these are for us the causes of cholera." In the fact, then, that cholera is communicable from the sick to the healthy through the medium of the specific discharges, we have conclusive evidence that the disease is eminently contagious. By contagious we mean communicable from the sick to the healthy, not by contact with the bodies of the sick, but with a material poison thrown off from their bodies and capable of being conveyed to a distance.

The non-recognition of the contagiousness of cholera, as the central fact in the history of the malady, has been the source of infinite confusion amongst medical writers, and of numberless preventible disasters in many parts of the world.

We propose now to refer to the evidence in favour of the proposition that cholera may be conveyed from an infected district to one previously healthy by human agency. The evidence upon this point is so abundant that the difficulty consists in selecting from a great mass of material. In Dr. Baly's Report (11, pp. 296 to 318) there will be found the particulars of the appearance of cholera in seventy-three towns, villages, and public establishments in England during the epidemic of 1848-9, subsequent to the probable introduction of infection. These numerous cases afford most indisputable evidence that cholera is a portable and a contagious disease. As an example, we select one case illustrative of the introduction of cholera into Titchmarsh, near Thrapstone (11, p. 300):

1. A butcher had been to Peterborough, and visited a house there, infected with cholera, on the 3rd October. His bowels became very loose on the morning of the 6th; he soon became collapsed, and died the same night.

2. His mother was attacked on the 13th, and lingered to the 24th. His wife, two daughters, and a son, were also ill with severe diarrhoea.

3. The woman who nursed the first case was attacked in his house on the 13th; moved to her own, 400 or 500 yards off, on the 14th; recovered.

4. This woman's daughter was attacked on the 17th; removed to her house, half a mile off; recovered.

5. The husband of the last patient was attacked on the 22nd. Nine cases (6 fatal) occurred within a few doors of the last patient between the 21st October and the 15th November. The sister of Case 5, who nursed Cases 4 and 5, was attacked on the 4th November, and died in twelve hours. Two men living next door to the first case were attacked on the 9th and 14th November; both died. A woman who nursed them was attacked on the 17th, and died in twelve hours.

There is abundant evidence to show that in numerous instances cholera has been imported by a ship having the disease on board. A remarkable instance is recorded by Deputy Inspector-General Barrow (Statistical Sanitary and Medical Reports, Army Medical Department,' London, 1866):-On the 9th April the steam-ship England arrived off Halifax (Nova Scotia), having cholera on board. A pilot, with an assistant and his son, went off to the ship in an open boat. Hearing that there was sickness on board, the men remained in the boat, which was towed at a considerable distance astern by a tenfathom rope. In this way the ship, with the boat in tow, was conducted to her place of anchor. The pilots then went on shore, and were never on board the infected ship.

In the course of the next two days both men were seized with cholera, and one died. Both men communicated the disease to their families. In the family of one there were three cases, but no death; in that of the other, besides the father, who died, there were four cases and two deaths. The only other cases of cholera at Halifax at that time occurred in the family of a man whose two children were seized after playing with some soiled bedding which had floated on shore from the infected steamer; one child died, the other recovered. The mother also took the disease, and died. Surely if disease was ever communicated by infection it was so in the case of these three families, the different members of which were in various ways brought into contact with the infecting material imported by the steamer.

We would remark in passing that Dr. Chasseaud's little work (9) contains most conclusive evidence of the importation of cholera, and its subsequent diffusion by contagion in Symrna and in the surrounding villages during the epidemics of 1848 and 1865, while in the work of Drs. Pirondi and Fabre (13) there is equally satisfactory evidence of the importation of the disease into Marseilles in 1865, and of its conveyance by human agency from one part of France to another during the earlier epidemics (see also that part of Dr. Baly's report which relates to the introduction of cholera into islands or new continents by human intercourse (11, pp. 139 to 155). An indirect proof of the contagiousness of cholera is afforded by the fact that the disease has never reached certain countries which, being separated from India by a wide expanse of ocean, and having little communication with that country, have escaped the infection. Amongst these countries are Australia, New Zealand, and the other Pacific Islands; the Cape of Good Hope and the southern part of the west coast of Africa; the Azores, Bermuda,

Iceland; the Faroe, Orkney, and Shetland Islands, and the western coast of South America.

In India it is, perhaps, more difficult to get conclusive evidence of contagion than in Europe, yet the records of the disease in India afford convincing proof of contagion. For example, Dr. Goodeve (10, p. 680) quotes from the report of the Indian Cholera Committee on the epidemic of 1861 some remarkable facts with reference to the introduction of cholera into the villages of British Gurwhal within the Himalaya mountains. In the early part of 1852 extensive works of irrigation at the foot of the mountains brought together several thousand workmen. Cholera broke out amongst them, and they fled, panic stricken, to their homes, which were generally at a distance of several days' journey in the interior of the hills. Up to this time cholera had been unheard of amongst the mountains. Many of the workmen died on their way home, many others were attacked after they reached their villages. Then cholera broke out among the other inhabitants of the villages, commencing in very many instances in the families of the men who had brought the disease from below. For a considerable time cholera was entirely confined to the places which had been in direct communication with persons suffering from the disease, but in the course of a few weeks it had become impossible any longer to trace such connection, and cholera became generally epidemic in the hills. Many of the first cases were carefully investigated, and it appeared to be proved beyond the possibility of a doubt that cholera was brought by human intercourse into a district which, up to that time, had been free from every sign of the disease.

Dr. Townsend, the Sanitary Commissioner for the Central Provinces of India, in his second report (3, pp. 168-9, &c.) shows that every district in which inquiries were instituted furnishes evidence of importation of the disease by human intercourse, and of its subsequent spread from person to person and from village to village.

It appears scarcely necessary to multiply evidence of this kind to prove that cholera may be conveyed from place to place by human agency.

In proceeding to discuss the precise mode in which the disease is communicated we shall have no difficulty in proving that the discharges from the stomach and bowels have the power to impart the disease. The following statement by Dr. C. Macnamara (12, p. 196) affords conclusive evidence upon this point. He says—

I may mention the circumstances of a case in which the most positive evidence exists as to the fact of fresh cholera dejecta having