GERM THEORY 23 



supply of a locality became infected, the disease spread among its 

 consumers. Budd of London was probably the first to detect the role 

 of infected water in the dissemination of Asiatic cholera. Finally the 

 discovery of the specific bacteria of cholera and other diseases removed 

 the last support of the theory of disease originating in miasmatic 

 conditions of the atmosphere. 



The "germ theory" of disease found lodgment in the brain of an 

 occasional genius many centuries ago. Just who first suggested it 

 and when are not easily determined, but the argument ran something 

 as follows: Alexandria was free from the plague. A ship from a 

 port where it prevailed came with sick on board. Those associated 

 with the new arrivals acquired the disease and it spread in an ever 

 widening circle until it prevailed throughout the city and extended in 

 a similar manner to other countries. The disease must be due to a poison 

 of some kind. It cannot be a chemical poison, like arsenic, but it must 

 be a living thing which finds its way from the body of the sick to those 

 of the well where it grows and multiplies and in so doing causes the 

 symptoms of the disease and death. Thus, man's reason, stimulated 

 by exact observation, caused him to conclude that an epidemic must 

 be due to a contagium vivum. He might theorize concerning this 

 living thing, but he could not demonstrate its existence. It was too 

 small for him to see. In the first century of the Christian era Varro 

 wrote that there are swamps in which grow animals so small that they 

 cannot be seen. They enter the body through the mouth and nose 

 and cause disease. Others wrote to the same effect. Probably the 

 first to see bacteria was the Dutch scientist and lens maker, Leeuwen- 

 hoek, who near the end of the seventeenth century described the 

 "animalculae" which he found under his microscope in the examination 

 of tartar from the teeth and diarrheal stools. In 1849 a village doctor 

 on the Rhine, with a crude compound microscope, saw rod-like bodies 

 in the blood of animals sick with anthrax and failed to find them in 

 the blood of healthy animals. The science of bacteriology may be 

 said to owe its birth to these observations. Independently, this work 

 was continued by Brauel, Davaine and others, but the founder of 

 exact and systematic knowledge concerning the causal agents of dis- 

 ease was the great Frenchman, Louis Pasteur. 



