ENTRANCE OF DISEASE 



MODE OF ENTRANCE OF DISEASE GERMS. 



Of the Passage of the Disease Germs into the Blood. 

 In all cases in which disease germs produce their 

 characteristic effects, they reach the blood. Until they 

 have entered this fluid there is no possibility of their 

 exerting any deleterious effects upon the system. 

 Having entered the blood, they grow and multiply, 

 and, as we shall see presently, become obstructed in 

 the smaller capillary vessels, in and around which 

 those changes occur, which give to each particular 

 contagious fever the characteristics peculiar to it, 

 and enable us to recognize and define it. 



With regard to the manner in which the minute 

 particles of contagious germinal matter gain access 

 to the blood, there has been much difference of 

 opinion, but many circumstances render it certain 

 that they may reach it from many different surfaces. 



Suspended in the air, they may pass towards or into 

 the air-cells of the lung at every inspiration. Some 

 of the lightest particles might reach the ultimate air- 

 cells where an exceedingly delicate membrane easily 

 penetrated by living particles alone separates them 

 from the blood. 



If living disease-germs fell upon the soft mucous 

 lining of the air passages, they would there find a 

 material if not adapted for their nutrition, at least 

 favourable for preserving them in a living state. 

 Through this they would gradually make their way 



