Bacteria 



the case, the reason is because they have either ex- 

 hausted all the food that they can get in the body or 

 else have made it uninhabitable for themselves by their 

 own poisonous excretions. These theories leave, how- 

 ever, out of sight a very important side of the question. 



The cells in the animal's body when a bacterial 

 enemy invades it are not dead but alive, and invariably 

 make some sort of effort to resist them. 



The only possible answer for such a live cell in an 

 animal body is to fight a poisonous bacterial excretion 

 by secreting something else. Such mysterious defensive 

 secretions are called anti-bodies, and may either be 

 antitoxins, which neutralise the toxins (that is, bacterial 

 excretions), or they may be bactericidal bodies which 

 kill the bacteria themselves. 



This response of live cells to bacterial enemies is 

 another clear case of " fitting reactions." 



We are obliged to mention here a rather disturbing 

 and agitating fact with regard to our own bodies, but 

 the reader must please consider it in a bright and hope- 

 ful spirit. There are, wandering everywhere within our 

 own bodies, multitudes of white blood corpuscles or 

 phagocytes, whose duty it is to destroy and devour any 

 objectionable microbes that have managed to enter us. 

 We have no control over these phagocytes, who are 

 entirely free and independent. 



When a foreign bacillus has entered our body, it 

 begins to give forth its poisonous excretions ; these pene- 

 trate to and eventually reach a phagocyte. The whole of 

 the latter's protoplasm is at once on the alert ; stimulated 

 and " anhungred " by the trace of this secretion, forth- 

 with it proceeds, crawling as rapidly as possible, towards 

 the bacillus until the supreme moment arrives in which 

 it engulfs or enfolds the unfortunate microbe within its 

 own jelly-like body and promptly digests it to death. 



56 



