THE PROGRESS OF VETERINARY SCIENCE. 517 



Contagious and infectious diseases may, I think, be divided into two 

 great classes, viz. those which are indigenous in a country, which are 

 inherent in its climate and soil, or have become acclimatised in it ; and, 

 secondly, those which are of foreign origin and which do not become ac- 

 climatised, which can only be reproduced to a limited extent, and for a 

 limited time, by virus freshly imported from those countries in which the 

 disease is indigenous. In the human subject we in England recognise 

 yellow fever as a foreign disease. Ships arrive at Southampton from the 

 West Indies with yellow fever on board ; but it spreads only to a very 

 limited extent in English climate and soil. The climate and soil do not 

 suit its development, and the virus dies out. Cholera is another some- 

 what similar disease. It is of foreign origin, and can be reproduced in 

 this country only so long as the strength of the imported virus sustains 

 itself. Gradually it weakens and dies out in English soil and climate. 



Now cattle plague was, and still is, essentially a foreign disease. If 

 sufficiently stringent regulations had been at once adopted, as the Vete- 

 rinary profession recommended, the disease might have been stamped 

 out at once, and the lives of many hundreds of thousands of animals, 

 valuable to man, might have been saved. The Veterinary profession had 

 long before realised this important distinction, and, therefore, recom- 

 mended slaughter. They were right ; but they were and are abused for 

 that recommendation. It may, however, be said that this was a new 

 disease, and that there was no reason to expect such dreadful ravages. 

 But this observation is untenable. The disease had long been known to 

 veterinary surgeons, and had been studied by several of them on the 

 steppes of Russia ; and they were therefore fully justified in their recom- 

 mendation of slaughter. In cholera in human beings it would be im- 

 possible to adopt the same stringent course. But if it could be applied 

 on its first appearance in a country which is not its natural habitat, I 

 doubt not but that it could be stamped out, and many thousands of lives 

 might be saved. 



1040. Home-lred Diseases. 



Whilst I am strongly of opinion that diseases of foreign origin, such as 

 cattle plague, may be stamped out by preventive measures, I look upon 

 the attempt to stamp out diseases natural to, or acclimatised in our 

 climate and soil, as useless and idle. For those diseases which are natural 

 to or acclimatised in our country, such as pleuro-pneumonia, foot-and- 

 mouth disease, etc., the germs of which exist throughout the length and 

 breadth of our land, I believe the measure restricting locomotion to be 

 more costly and irksome than successful in result. 



If these diseases, which are always in the country, can be spread, as 

 alleged, by so many causes, by air, by water, by passage of cattle over 

 ground, by flies, by birds, by hares and rabbits, etc., what can be the use 

 of restriction 1 Can you bind the wind ? Can you stop the flow of water ? 

 Can you limit the flight of flies and of birds ? 



Further, I look on the now prevalent idea that these diseases are 

 usually due to infection or contagion as a source of great evil. I believe 



