PREVENTIVE MEDICINE—-BOYD 519 
milk in an outbreak of typhoid at Penrith. The first scientific 
demonstration of the transmissible character of an infectious dis- 
ease was performed by Villemin with tuberculosis, in 1865, while 
the first demonstration of the etiological relation of microparasites 
to disease was accomplished by Pasteur in the case of anthrax in 
1876, thus substantiating the earlier beliefs of Kircher and Plenciz. 
Patrick Manson recognized the first known insect-transmitted dis- 
ease, when he found that mosquitoes transmit FYilaria bancrofti. 
From the time of Jenner no progress in artificial immunization 
was made until Pasteur demonstrated the protective power of his 
anthrax vaccine on sheep in 1881, and in 1885 extended the same 
principle to the treatment of rabies. 
In 1893, Smith and Kilbourne, two Americans, discovered the 
cause and means of transmission of the first known insect-trans- 
mitted protozoal disease, namely Texas fever of cattle. 
The importance of carriers in the perpetuation of typhoid fever 
was first recognized by Robert Koch, who called attention to them 
in 1902. Carriers of the diphtheria bacillus had been observed 
before this, but their importance was not recognized. 
The results which can accompany the application of the principles 
of preventive medicine received their first great popular demonstra- 
tion by Gorgas, when he eradicated yellow fever and malaria from 
Havana and the Canal Zone. This accomplishment may be con- 
sidered to mark the beginning of active public interest in the possi- 
bilities of preventive medicine, a situation which may be said to 
characterize the present day. 
REFERENCES 
Sep¢wick :“ Principles of sanitary science and the public health.” Chapters 
Li, TES FV; 
Leviticus, Chapter XIII: 14. 
Deuteronomy, Chapter XXIII: 13. 
Eacer: “ The early history of quarantine.” Yellow Fever Institute Bull. No. 
12, U. S. P. H. and M. H. Service. 
Mortality Statistics. Published annually by the Bureau of Census since 
1900. 
Goreas: “ Sanitation in Panama.” 
Newman: “An outline of the practice of preventive medicine.” British Min- 
istry of Health. 
Pearl, Raymonp: “The biology of Death” (a series of papers). The Scien- 
tific Monthly, vol. xii, 1921. 
Monthly Bulletin of the Department of Health, New York City, vol. iii, 
May, 1913. 
McFarianp: “ Textbook upon the Pathogenic Bacteria and Protozoa.” Part 
One—Historical Introduction. 
