GENERAL REMARKS UPON INFECTION 7 



What has already been said will, it is hoped, make 

 the following definition of an infectious disease quite 

 clear. An infectious disease is one which is caused 

 by the introduction of living disease germs within the 

 body of a susceptible individual. This definition in- 

 cludes the idea of the reproduction that is, multipli- 

 cation within the body of the specific disease germ, 

 which must be living and thus capable of reproduc- 

 tion in order to produce an infectious disease. More- 

 over, it must find conditions favourable for its 

 reproduction within the body or it will not give rise 

 to any disease process that is, the individual must 

 be susceptible. 



