Bacteria 



Nor are the other live cells of our body mere passive 

 spectators of the prowess of their police phagocytes. 

 They do what they can and secrete mysterious sub- 

 stances called opsonins, which somehow paralyse or 

 entangle the bacillus so that it falls a helpless prey to 

 the "polymorphonuclear leucocyte/' which is the correct 

 style and designation of the phagocyte. 3 



Not only so, but those tissues which are set apart 

 for the production and formation of phagocytes, work 

 more energetically when a bacillus invasion is proceed- 

 ing and turn out a much larger number of phagocytes 

 than usual. 



There is a strange difference between individuals in 

 these matters. The bodies of certain people are rich 

 in opsonins, so that they are well able to resist bacteria, 

 whilst others are decidedly feeble and weak "opsoni- 

 cally." The researches of Messrs. Leishman and Wright 

 must be consulted for further details as to the " opsonic 

 index," &c. 



There are several methods by which people can be 

 made immune to some particular infectious bacterium. 

 One ingenious method consists in first isolating your 

 race of bacteria and then turning that race into a feeble 

 and inefficient variety, which will do no great harm to 

 the individual but yet prevent any subsequent accidental 

 invasion of the original wild bacterium from establishing 

 itself. 



Such a wild germ would find the food material 

 exhausted and the ground poisoned by the feeble race 

 which preceded it. 



Pasteur's method with the germ of hydrophobia 

 consisted in exposing the colonies for a greater or less 

 period to a current of air. The results of his experi- 

 ments are quite remarkable. 



Before 1886, 16 per cent, of all persons bitten by 



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