BACTERIOLOGY IN A NUTSHELL. 



Channels of 

 Entrance^ 



Period of 

 Incubation. 



Period of 

 Invasion. 



Why 



Multiplication 



Ceases. 



wounds and the skin, all form channels where- 

 by infection is conveyed to the various parts 

 of the body which are seats of attack for 

 pathogenic bacteria. 



An incubation period, which varies in dura- 

 tion, is common to all forms of disease caused 

 by the invasion of bactei-ia. During the incu- 

 bation period there are no symptoms of the 

 disease. The germs have gained admission 

 to the body by one or other channel of entrance 

 and a war is being waged between the invaders 

 and the antagonistic cells of the body already 

 spoken of as phagocytes and opsonins. Under 

 favorable circumstances the invaders do no 

 harm, they are destroyed by their foes and are 

 thrown ofif from the body in the excretions. If 

 the powers of resistance are weakened in any 

 way, by the presence of any other disease, for 

 instance, the influence of the phagocytes is lost 

 and the period of incubation ends in another 

 period wherein the power of the invading 

 bacteria is made manifest and symptoms arise 

 followed by more or less serious results. 



In each specific disease the infection is 

 thrown off from that part of the body which is 

 the seat of the invasion. 



During the course of a communicable or 



specific disease there comes a time when there 



is no longer any suitable nourishment for the 



growth and development of the micro-organ 



so 



