MAN AND THE MICROBE 7 



Greeks were scientific or not, they aimed to be scientific, and they firmly 

 implanted along with all their error, a zeal for the scientific truth about 

 nature and a confident belief in the possibility of its ultimate attainment. 



Prom Hippocrates down to our own times, then, we find that the ex- 

 planation of diseases of all kinds has been sought by scientific men, not 

 in the activities of spiritual beings, but in the workings of natural law. 

 Eesults were almost nil, however, so far as the communicable diseases are 

 concerned, until the nineteenth century when a sudden and rich fruition 

 took place here, as in all fields of the biological sciences, as a result of a 

 simple mechanical discovery, the lens-maker's trick of the achromatic 

 objective, which made possible the modern high power microscope and 

 revealed all at once a new and stupendous world — "The world of the 

 infinitely little." 



It is true that Leeuwenhoek and other early naturalists had seen the 

 microbes with their primitive simple lenses. It is true that still earlier, 

 in the sixteenth century, the Veronese physician, Fracastorius conceived 

 the communicable diseases as due to " seminaria contagionum," minute 

 particles capable of reproduction in appropriate media and having many 

 of the attributes we know to be characteristic of the bacteria to-day. The 

 Roman author Varro, in writing on the choice of sites for a farm house 

 cautions the builder against the neighborhood of swampy ground "be- 

 cause certain minute animals, invisible to the eye, breed there, and borne 

 by the air, reach the inside of the body by way of the mouth and nose, 

 and cause diseases which are difficult to get rid of." Nevertheless, so 

 far as any scientific demonstration of their nature was concerned, the 

 communicable diseases remained as much a mystery in 1800 as in 

 400 B.C. 



It was the achromatic objective, perfected about 1840, which first re- 

 vealed the ubiquity of microbic life and its special richness in connection 

 with the processes of fermentation and decay; and it was of profound 

 moment in the history of medicine and sanitation when Pasteur proved, 

 against the opposition and the ridicule of the great Liebig and a host of 

 lesser critics, that fermentation was the result of the action of microbes, 

 little living things which entered into the fermentable fluids and 

 grew and multiplied there, the fermentation being the result of their 

 powerful chemical secretions. The "little leaven that leaveneth the 

 whole lump" was shown to be a self-propagating plant, and the many 

 desirable and obnoxious decompositions to which sugary fluids are sub- 

 ject, each the result of a special microbe. 



The analogy between fermentation and disease must have sprung 

 into many minds, with the hope that the solution of the latter problem 

 too might be found by the study of microscopic life. It was again 

 Pasteur who by his rigid experimental method extracted the truth from 

 the mass of good and bad guesses of those who had preceded him. In 

 his study of the disease which threatened to wipe out the great silkworm 



