HEALTH AND DISEASE 



431 



by giving them gradually larger doses of the diphtheria toxin or 

 poison. The serum (or liquid part) of the blood of these horses is 

 then used to inoculate the patient suffering from or exposed to 

 diphtheria, and thus the disease is checked or prevented altogether 

 by the antitoxin injected into the blood. 



Vaccination. Smallpox was once the most feared disease in 

 this country; 95 per cent of all people suffered from it. As late 

 as 1898, over 50,000 persons lost their lives annually in Russia from 



this disease. It is probably not caused 

 by bacteria, but by a tiny animal para- 

 site. Smallpox has been brought under 

 absolute control by vaccina- 

 tion, the inoculation of man 

 with the substance (called 

 virus) which causes cowpox in 

 a cow. Cowpox is like a 

 mild form of smallpox, 

 and the introduction of 

 this virus gives complete 

 immunity to smallpox for several years 

 after vaccination. This immunity is 

 caused by the formation of a germicidal 

 substance in the blood, due to the in- 

 troduction of the virus. 

 The Work of the Department of Street Cleaning. In any 

 city one menace to the health of its citizens exists in the refuse and 

 garbage. The city streets, when dirty, contain countless millions 

 of germs which have come from decaying material, or from people 

 ill with disease. In most large cities a department of street 

 cleaning not only cares for the removal of dust from the streets, 

 but also has the removal of garbage, ashes, and other waste as a 

 part of its work. The practice of putting open cans contain- 

 ing ashes and garbage into the street for disposal is an indirect 

 means of spreading disease, for flies breed and germs may thrive 

 there. The street-cleaning department should be aided by every 

 citizen; rules for the separation of garbage, papers, and ashes should 

 be kept. Garbage and ash cans should be covered. The practice 

 of upsetting ash or garbage cans is one which no young citizen should 



A l>:ul condition of the streets, 

 lower Kust Side, New York. 



