64 SCIENCE REMAKING THE WORLD 



Robert Koch and others began to use aniline dyes to 

 stain the microscopic disease germs and to catch their 

 pictures on the photographic plate, developed by coal- 

 tar chemicals. From that time on, as he said, dis- 

 coveries fell into the lap of the investigator like ripe 

 fruit. In 1882 he discovered the bacillus of tuberculosis 

 and in the following year the bacillus of Asiatic cholera. 



The bacillus of typhoid fever was discovered in 1880 

 and in 1896 a serum was prepared to prevent it. What 

 this has meant for public health we are all vaguely 

 aware, but a few figures may fix our ideas. In our war 

 with Spain where we had 107,973 men in encampments, 

 20,738 of them were taken down with typhoid and 

 1,580 of them died of it. But in 1912, when we had 

 12,801 men under similar conditions stationed on the 

 Mexican border, only two cases developed, while in the 

 Great War there were only 227 deaths from fever in all 

 the American armies during two years. This microbe 

 that had been the most formidable foe in previous wars 

 has been finally conquered because we know where it 

 lives and how it is carried and can even prepare the body 

 in advance to resist it, if in spite of our precautions it 

 gains entrace. 



It is not a matter of chance that certain dyes have 

 been found valuable as drugs. The same thing that 

 makes them good dyes makes them good medicines; 

 that is, their ability to attach themselves to some par- 

 ticular kind of animal or vegetable substance. Many of 

 our most dangerous diseases are, as we now know, due 

 to minute vegetable or animal parasites, bacteria or 

 protozoa, that flourish in the blood and at our expense. 



