CHAPTER VIII. 



CONSUMPTION AND THE WAYS IN WHICH IT IS 

 SPREAD BY DUST. 



THE germ which causes consumption or 

 tuberculosis is a minute slender rod-like 

 body about one ten-thousandth of an inch in 

 length, and is called the Bacillus tuberculosis. 

 It does not grow in nature outside of the bodies 

 of men and a few species of warm-blooded 

 animals. It may, however, remain alive for 

 a long time when dry as in the soil or air. 



In the bodies of some animals and in the 

 bodies of many men it does not ordinarily 

 flourish or even grow at all, for reasons which 

 we do not understand. The proper tempera- 

 ture may be present and moisture and nutritive 

 material in abundance, but for some unknown 

 reason it will not grow. There are other in- 

 dividuals and other animals which seem to 



