68 



ESSENTIALS OF BACTERIOLOGY. 



The serum will hinder the growth of germs, and when bac- 

 teria are injected directly into the blood, they soon disappear. 

 They cannot osmose ; they collect in the liver, spleen, and 

 marrow of bones, and the corpuscles aid growth. The serum 

 of different animals acts differently upon the same microbe. 



Cellular Theory of Metschinkoff. The phagocytes, as he 

 terms them, are anti-microbic. They are the soldiers which 

 endeavor to destroy the enemy. If the cells are strong, they 

 become the victors ; if the bacteria are stronger, the bacteria 

 conquer and eat up the cells. 



But this theory, though having many supporters, is opposed 

 on sufficient grounds, the one reason being that whenever cells 

 become the residence of live bacteria they suffer ; and if Mets- 

 chinkoff and others have seen bacteria directly enter cells and 

 disappear, it is that they were destroyed before, and that the 



leucocytes only acted as scav- 

 engers. (Fig. 42.) 



And the late researches 

 with the serum of the blood 

 freed of its cellular elements, 

 and being directly anti-bac- 

 teric, would seem to place the 

 phagocytes in the background. 

 The matter is, however, by 

 no means settled. 



To sum up, we have patho- 

 genic microbes such as give 

 rise to products injurious to the animal organism. The infec- 

 tious ones can overcome the natural resistance of the animal 

 body and develop therein. The bacteria can have this activity 

 lessened or destroyed by agents which are injurious to their 

 products, so as to render them inactive. 



FIG. 42. 



Phagocytes of Metschinkoff: <i. Bacillus 

 entering ; ft. Bacillus inclosed. 



