1894 THE MICROSCOPE. 35 



not. By combining these various tests, bacteria may be 

 identified when the microscope alone cannot do it. For 

 understanding all these details, one needs a Manual of 

 Bacteriology like that of Dr. Sternberg, or a little com- 

 pend like that of Dr. M. V. Ball. 



These minute organisms are present when the diseases 

 named occur but some of them are sometimes present 

 when the disease does not occur. Instead of saying that 

 they cause the disease it is safer to say that when these 

 germs find the system enfeebled or otherwise favorably 

 disposed to harbor them disease is able to arise from the 

 combined conditions, and it is quite certain that the sev- 

 eral diseases could not occur provided the attendant 

 germs were annihilated or kept out of the system. 



These then are all communicable diseases and we 

 should know in what manner the infection is transferred 

 and so seek to avoid it. Happily we are able to say 

 what the method of transmission is in many cases and to 

 avoid it. For instance, we know that a consumptive has 

 in his saliva millions of these germs, that if he spits upon 

 floors, the ground, etc., the liquid soon dries up and the 

 dried germs go floating in the air, to be breathed into the 

 lungs of thousands of passers by. If the recipient is in 

 sufficiently robust health no harm comes, but if the germ 

 gets a start in the lungs it will multiply indefinitely and 

 until death or cure ensues. Should every consumptive 

 carefully preserve and burn all of his expectorations, the 

 disease would soon be banished from the earth. 



In 100 cases studied by one observer, it was found that 

 80 had been inoculated by occupying rooms which had 

 previously been occupied by consumptives without proper 

 methods of cleansing having been employed. Public 

 drinking cups are another means of communicating in- 

 fection. 



The microscope has proved that we cannot live for 

 ourselves alone. The interest of one is the interest of 



