Ill ON ANIMAL LIFE 99 



isms are of vital importance. Many diseases 

 are now known, and others suspected, to be 

 entirely due to Bacteria and other minute 

 forms of life (Microbes), which multiply in- 

 credibly, and either destroy their victims, or 

 after a while diminish again in numbers. We 

 live indeed in a cloud of Bacteria. At the 

 observatory of Montsouris at Paris it has 

 been calculated that there are about 80 in 

 each cubic meter of air. Elsewhere, however, 

 they are much more numerous. Pasteur's re- 

 searches on the Silkworm disease led him to 

 the discovery of Bacterium anthracis, the 

 cause of splenic fever. Microbes are present 

 in persons suffering from cholera, typhus, 

 whooping-cough, measles, hydrophobia, etc., 

 but as to their history and connection with 

 disease we have yet much to learn. It is 

 fortunate, indeed, that they do not all at- 

 tack us. 



In surgical cases, again, the danger of com- 

 pound fractures and mortification of wounds 

 has been found to be mainly due to the pres- 

 ence of microscopic organisms ; and Lister, by 

 his antiseptic treatment which destroys these 



