82 Kansas Academy of Science. 



demned him for this disregard of authority. Following Ver- 

 salius came Harvey with his monumental discovery of the cir- 

 culation of the blood. 



VII. THEORY OF MICROBES. 



Medicine now took many avenues of progress. It is with 

 the role that the microbes play in disease that we are especially 

 concerned, and we must now limit ourselves to those activities 

 concerned with the development of the germ theory of disease. 



It was in the seventeenth century — the century made famous 

 b> Shakespeare, Bacon, Milton, Harvey, Malpighi and Galileo 

 — that the Dutch lens maker, Leeuwenhoek, began his studies 

 of these minute agencies of death. Perhaps the honor of the 

 discovery of the microscope belongs to Galileo, as this instru- 

 ment is so closely related to the telescope. At any rate, while 

 he studied the firmament, Leeuwenhoek began the study of the 

 infinitely small life forms that surround us. He saw animal- 

 culse in water and saliva. He was interested in the origin and 

 size of these microorganisms. Not until two hundred years 

 afterwards however, was the great significance of Leeuwen- 

 hoek's discovery appreciated, when the relation of these in- 

 visible life forms to disease was realized. 



Just when the germ theory of disease had its inception is 

 difficult to state. Like most great truths, it was likely the 

 growing product of many centuries. Sir Harry Johnston has 

 said: 



"Not only did the growing culture of Neolithic and early metal ages 

 begin to preceive danger in the fly, in the locust, bug, tick and mosquito, 

 but an instinctive dread was felt of the invisible germ, the minute organ- 

 isms which were not to be visually perceived by men till the seventeenth 

 century of the Christian era, and not to be in reality appreciated and 

 understood till about fifteen years ago. , The instinctive belief in the 

 "germs" and the spread of the germ diseases was undoubtedly at the 

 basis of the preposterous class regulations developed by the Aryan in- 

 vaders of a Negroid, Australoid, India." 



One of the oldest specific references to the role that germs 

 play in the causation of disease is found in the "De Re Rustica" 

 of Tarentus Rusticus, who states : 



"If there are any marshy places, little animals multiply, which the 

 eye cannot discern, but which enter the body with the breath through 

 the mouth and the nose and cause grave diseases." 



Columella and Kirscher propounded the same theory even 

 before the time of Leeuwenhoek. To the latter, however, be- 

 longs the credit of first having viewed these microorganisms. 



