THE METAZOA 



whole body without affecting any of its 

 cells except just where the cells have been 

 injured by the needles; there they at once 

 begin to form abscesses. The uninjured 

 cells are then said to be endowed with a 

 vital resistance to the invaders, which is 

 wanting in those cells which have been 

 devitalized by injury. A third line of de- 

 fence is found in the healthy blood itself, 

 which contains well-identified ingredients 

 called opsonins, which enable the white 

 corpuscles of the blood to attack the in- 

 vading bacteria and eat them up. 



But what is this all-important vital 

 resistance? We need not say how im- 

 portant this is when, if a colony of tubercle 

 bacilli finds a lodgment in a man's lung, 

 his prospects will then depend on his local 

 or general stock of vitality. The lower 

 this is the sooner his funeral. 



Meantime we have been reading the 

 assertions of a school of biologists, that 

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