FROM PARACELSUS TO HARVEY 



demonstrated by Marcello Malpighi (1628-1694) in 

 1 66 1. By the aid of a lens he first saw the small 

 "capillary" vessels connecting the veins and arteries 

 in a piece of dried lung. Taking his cue from this, he 

 examined the lung of a turtle, and was able to see in it 

 the passage of the corpuscles through these minute 

 vessels, making their way along these previously un- 

 known channels from the arteries into the veins on 

 their journey back to the heart. Thus the work of 

 Harvey, all but complete, was made absolutely entire 

 by the great Italian. And all this in a single genera- 

 tion. 



LEEUWENHOEK DISCOVERS BACTERIA 



The seventeenth century was not to close, however, 

 without another discovery in science, which, when 

 applied to the causation of disease almost two centuries 

 later, revolutionized therapeutics more completely 

 than any one discovery. This was the discovery of 

 microbes, by Antonius von Leeuwenhoek (1632-1723), 

 in 1683. Von Leeuwenhoek discovered that "in the 

 white matter between his teeth" there were millions 

 of microscopic "animals" more, in fact, than "there 

 were human beings in the united Netherlands," and all 

 "moving in the most delightful manner." There can 

 be no question that he saw them, for we can recognize 

 in his descriptions of these various forms of little 

 ' ' animals ' ' the four principal forms of microbes the 

 long and short rods of bacilli and bacteria, the spheres 

 of micrococci, and the corkscrew spirillum. 



The presence of these microbes in his mouth greatly 

 annoyed Antonius, and he tried various methods of 



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