8,639 cases of ship fever, and 5,424 interments took place at Grosse Isle, in the St. Lawrence, where a monument still stands to the memory of the devoted physicians who died at their posts ministering to those unfortunates. From the ports the disease spread inland, and to-day the graveyards of many towns along the great inland waterways have numerous memorials of the years of the ship fever, while the cholera of 1849 added still further to the horrors of the sea-voyage, and to the dangers to the populations along the great immigrant routes of the St. Lawrence and the Erie Canal. The first great measure of reform in England arising out of this condition of affairs was the abolition of the Corn Laws, described by Lord John Russell as "the blight of commerce, the bane of agriculture, the cause of bitter division among the classes, the cause of penury, fever and crime among the people." How the hopes of the people were lifted up, accompanied by the deep stirrings of the public conscience, may be seen in the literary romances of the time of such writers as Canon Kingsley in his "Yeast" and "Alton Locke," the one dealing with the conditions of the agricultural laborers, and the other with the employees of sweat shops, and of Charles Dickens, who in "Little Dorrit" and "Nicholas Nickleby" makes scathing attacks on the prison system and the Yorkshire proprietary schools. Such are but a few of the influences which gave momentum to the social reforms following financial reforms, the results of the work of Russell, Cobden and Bright. Political changes retarded somewhat the development of the public health measures instituted by the "Health of Towns Act" of 1849, and of the first Board of Health, whose existence practically ended with the report of 1854, prepared by Chadwick, now Sir Edwin. Its work was thereafter placed under the Local Government Board, combined with the Poor Law administration. Of this great sanitary reformer, whose work now came to an end, the political economist. John Stuart Mill, in writing to him, said: "I need only mention the Sanitary Department, the importance of which, now so widely recognized, you were amongst the very first to press upon a careless public." Under this first Board of Health was appointed Dr. John Simon as the first medical officer of health, and the City of London Reports, 1849-1854. supply us with the first series of public health reports in which the now every-day subjects. of "House Drainage," "Public Water Supplies and Their Pollution," "Social Position of the Poor and Their Overcrowding," "Offensive Trades," "Smoke Nuisances," etc., are systematically dealt with. With the instincts of a general, Dr. Simon began, in 1853.

to prepare for the cholera, which again appeared in 1855, and he has given us in the report of that year not only a history of its progress, but the first comprehensive summary of the sanitary conditions upon which the prevalence of cholera depends. I cannot forbear quoting a paragraph which illustrates how the facts developed in the fields of pure science had invaded the field of practical medicine. He says: "Thus, then, our position stands. Scientific prediction of phenomena can arise only in the knowledge of laws. That the phenomena of this disease, however capricious they may seem, are obedient to absolute uniformity as yet. beyond our ken, are enchained by that same rigid sequence of cause and effect which is imposed on all remaining Nature, it would be impossible to doubt." But with regard to larger views on public health we have only to follow the subjects discussed by Dr. Simon in his five successive London Health Reports. In that of 1854 he especially deals with a subject of intense interest to many members of this Association, viz., "The Establishment of a Department of Public Health, presided over by a Minister of the Crown." He says: "But at least as regards its constituted head sitting in Parliament, his department should be, in the widest sense, to care for the physical necessities of human life." Such separate department with its Minister of Health was not to be; nevertheless, the General Board of Health was continued, and we find Dr. Simon again, in 1858, addressing the Right Honorable the President of the Board when making a report based upon the lectures of Dr. Greenhow, Lecturer on Public Health in St. Thomas Hospital, "On the Present Wasteful Expenditure of Human Life in England." Utilizing the Registrar-General's statistics of annual deaths during the twenty years since the Registration Act was passed, this paper deals with the causes of deaths, pointing out that "thousands of deaths annually result from diseases which are in the most absolute sense preventable," and goes on to point out in detail the different diseases included in this category. Successive annual reports presented new series of facts, each repeating with gathering strength the truths of preventive medicine; and we find that the proverb: “Gutta cavat lapidem," was here, as ever, true, for with the reappearance of cholera and typhus in 1865, public health measures were instituted having a scope hitherto unknown. The Government ordered certain scientific researches to be undertaken; we find medical officers sent to the Continent to study these diseases in the seats of their prevalence, and special investigations instituted in those towns where these diseases had

already appeared in England. Expert chemists, too, were engaged in studying the physiology of diseases in man, and now for almost the first time we find Governmental intervention in the case of outbreaks of disease in animals. Of these the most important was that by Professor Granger into the causation of rinderpest, which caused enormous losses of cattle both in England and on the Continent. It is in the report of 1869 that we find Dr. Simon first referring to those discoveries which have shed undying glory upon the name of Pasteur. He says: "It will now be seen that the views indicated in Dr. (Burdon) Sanderson's report with regard to the agencies of morbid infection are the views of Schroder and M. Pasteur on the agencies of fermentation and putrefaction.” Throughout all this period of legislative progress there had been developing with increasing momentum the influence of those workers in pure science whose early labors have already been referred to in some detail. From time to time workers in the field of natural history had expressed views based upon variations in type through environment of both plants and animals; but not until the "Origin of Species," by Charles Darwin, was published in 1859, had any scientific hypothesis capable of accounting for biological evolution been given to the public. In 1863 Thomas Henry Huxley published "Man's Place in Nature," and to these works must be credited much of the growth of that method of thought which has been carried into every field of scientific research during the latter half of the century. To comprehend how the scientific imagination was directed into a hitherto untrodden field, we have to turn to the labors of a school of workers in France, soon to become famous through the discoveries mainly due to the labors of Pasteur, known to his countrymen, as to all others, as le Grand Maître. He may, indeed, in the Carlylean sense, be called a "Poet of the Unseen." Following, as a chemist, the studies of Spallanzani and Gay-Lussac in the field of fermentation and putrefaction as applied especially to beer, he was soon attracted by Cagniard Latour's and Schwann's experiments proving the relation of the yeast-cells present to beer fermentation at a time when Helmholtz had seemingly been forced to again support Liebig's stoutly maintained oxygen theory. But in 1857 Pasteur had established the vitalistic theory beyond question, when he proved the presence of rod-like cells distinct from yeast-cells by cultivating a new species of germ in sugar as present also in the souring of milk, wholly apart from albuminoid substances. It became his firm conviction. that the fermentative process depended upon the life of the organ

isms present; and by the introduction of culture solutions he gave us the first step in that science which we now term bacteriology. Following this came that other remarkable discovery that certain organisms to which he gave the name anaerobes were paralyzed by the presence of that very oxygen which, till now, had been supposed to be the very essence of fermentative changes in organic substances, and soon proved that the real change was that of the fixation of oxygen during the growth of the bacteria themselves. But this germ theory had many battles to fight before it succeeded against the school of Liebig, especially prominent amongst whom was Pouchet, who taught an old doctrine of spontaneous generation. Not till the battle was renewed in England by Dr. Bastian, as late as 1876, again to be driven out of court by the beautiful experiments of Tyndall on germless air, as shown by rays of light, was the germ theory of omnis cellula a cellula, or omne vivum ex ovo, to take its place as the discovery which has absolutely transformed medical and surgical practice during the last quarter of the century and given us a practical working basis for that isolation and disinfection in contagious diseases which has reduced their prevalence and mortality to an extent beyond the most sanguine dreams of the early apostles of the new doctrine. Never was prophecy being more truly fulfilled than that of Pasteur: "Il est au pouvoir de l'homme de faire disparaitre de la surface du globe les maladies parasitaires, si, comme c'est ma conviction, la doctrine de la génération spontanee est une chimere." All will recall those experiments, published first in 1877, when this savant, who, at first with such trepidation, trespassed on the field of medicinefor, as he said, he was a chemist and neither physician nor veterinarian-gave to the world practically all we to-day know regarding anthrax. As in the field of fermentation, others, as Pollender, Rayer and Davaine, and Robert Koch, had already discovered the rod-like bodies in anthrax blood; but it required the wizard touch of Pasteur to give life and meaning to their studies. Never has romance had more fascination than the story of how Pasteur not enly proved the rod forms to be the cause of the disease, but also showed that the slight difference in the blood temperature of men, animals and fowls played a governing part in the propagation of the disease; and finally, as he showed in 1881, that by heat the virus could be attenuated until vaccine could be prepared for inoculation against the disease. In the words of his disciple and assistant, Roux, "medicine had never before witnessed such perfection in experiment, such rigor in deduction, such certainty of application."

His further work in the field of immunity, especially with regard to rabies, is now common knowledge, while millions of francs have been saved to France through inoculation with anthrax vaccine, and hundreds of lives have been saved from death through the vaccine against rabies. The establishment in Paris of the Pasteur Institute, that magnificent international monument to the genius. of the "Great Master," has become for all of us an oft-told tale. Of him, in the closing years of his life, an intimate friend has written, after describing his personal appearance: "That is Pasteur as he appeared to me-a conqueror, who will some day become a legend, whose glory is as incalculable as the good he has accomplished."

THE PERIOD OF ELABORATION AND DEVELOPMENT.

As will have been noted, Pasteur's first great discovery, that of the bacillus of anthrax, in 1876, marks the beginning of the fourth quarter of the century, which we have designated the "Period of Elaboration and Development." This is, too, the period which may be said to mark the beginning of what we call Listerism in surgery. It was at this time that Tyndall addressed a letter to Pasteur referring to renewed attacks on the germ theory and speaking of "the unattackable exactitude of your conclusions." It was, too, the year of the Centennial Exhibition in Philadelphia, and the holding of the first Public Health Congress in America, shortly to be followed by the outbreak of yellow fever in the valley of the Mississippi, which hastened the establishment of the National Board of Health of brief but happy memory-and which gave the impulse owing to which health boards have been established in almost every State or Province of North America. In the Republic of Mexico we also find that a Supreme Board of Public Health had been formed as early as 1841, placing that republic in the first rank amongst us in recognizing the duty of the State to deal with public health as a national matter; yet, as pointed out by Dr. Orvananos, it was not till that remarkable man, General Diaz, was made President, in 1876, that this Board was established on a permanent basis. Thenceforth the evolution of public health work in Mexico has been continuously directed by our confrère, Dr. Liceaga, whose labors during a quarter of a century for his country and for our science entitle him to a first place amongst the sanitarians of this continent, and, indeed, of the world. In no country that I am aware of does there exist to-day a more complete sanitary organization, or one in which the legislative, administrative and scientific functions are better co-ordinated or more efficiently