146 THE WONDERFUL CENTURY. CHAP. xiv. 



our organism; they then increase rapidly, and are in 

 many cases able to destroy us. 



We learn from this marvellous discovery that, so 

 long as we live simply and naturally, and obey the well- 

 known laws of sanitation, so as to secure a healthy condi- 

 tion of the body, the more dreaded zymotic diseases will 

 be powerless against us. But if we neglect these laws 

 of health, or allow of conditions which compel large 

 bodies of our fellow-men to neglect them, these disease- 

 germs will be present in such quantities in the air and 

 the water around us that even those who personally live 

 comparatively wholesome lives will not always escape 

 them. 



We learn, too, another lesson from this latest dis- 

 covery of the secrets of the living universe. Just as we 

 saw how, physically, dust was so important that not only 

 much of the beauty of nature but the very habitability 

 of our globe depended upon it, so we now find that the 

 most minute and most abundant of all organisms are 

 those on which both our means of life and our preserva- 

 tion from death are dependent. For these minute bac- 

 teria of various kinds are present everywhere in the 

 air, in the water, in the soil under our feet. Their func- 

 tion appears to be to break up by putrefactive processes 

 all dead organized matter, and thus prepare it for being 

 again assimilated by plants, so as to form food for ani- 

 mals and for man ; and it seems probable that they pre- 

 pare the soil itself for plant-growth by absorbing and 

 fixing the nitrogen of the atmosphere. They are, in 

 fact, omnipresent, and under normal conditions they are 

 wholly beneficial. It is we ourselves who, by our 

 crowded cities, our polluted streams, and our unnatural 



