Page:The healing art in its historic and prophetic aspects - the Harveian oration delivered before the Royal College of Physicians, Oct. 19, 1885 (IA b21908199).pdf/27

 tending towards great truths, we find that in every branch into which pathology is artificially separated improvement is taking place. The causation of disease-etiology-it is now known, must be sought in disturbances of our surroundings, or in defective inherited tendencies. How immeasurable is the distance which separates the mental attitude of the inquirer of to-day, engaged in tracing the causation of an epidemic disease, from the mystics who bewildered themselves with the notions of malignant spirits, of evil humours, or even recently of epidemic waves."

To illustrate especially the advance we have made in our knowledge of etiology, I would select but a single point, that is, the practice of arresting the diffusion of disease by limiting the spread of contagion.

This practice was illustrated on a gigantic scale by the Rinderpest, or Cattle Plagne, which appeared in this country in 1865. Towards the end of June in that year a few bullocks, imported from Revel, bringing with them the infection of cattle plague, were sold in the Metropolitan Cattle Market. From this single centre the disease spread step by step throughout the country until it had established 25,000 foci of infection within the year. Then a remedy was applied: all traffic of cattle was stopped; all infected beasts were killed, and all healthy bovine animals with which they had come in contact. The pestilence was stayed, but not until 300,000 animals had died or been killed, with a loss to the country, at a low estimate, of three millions sterling, and an indirect loss to the same amount. All this might have been spared if it had been possible for the authorities, by a better knowledge of the nature of the disease, and of its remedy, to extinguish it at its single primary focus by the sacrifice of a small number of animals at the cost of a few pounds. (5)

The system of preventive treatment which thus proved so successful in the case of these lower animals has, as far as