146 The Story of the Bacteria 



and thrive upon poisons which without these 

 curious proclivities would inevitably damage 

 or destroy them, and us. This power of the 

 body cells and organs to destroy and dispose 

 of internal waste and poisonous material is, 

 then, the second of our great protective 

 agencies against disease. 



The bacterial poisons are disposed of through 

 the very agencies which are constantly guard- 

 ing our bodies from harm by the home-made 

 poisons which we ourselves elaborate. These 

 agencies consist largely of new chemical 

 unions into which the poisons are forced to 

 enter, thus losing their identity and their 

 harmfulness. 



Another important safeguard of the body 

 is certain tiny cells, the most significant of 

 which we have glanced at in an earlier chapter, 

 the leucocytes or white-cells of the blood (see 

 Plate XI., i). Although the body can main- 

 tain its form and structure and go on doing 

 its work, often beyond the orthodox threescore 

 years and ten, it is in fact constantly changing. 

 New cells are forming and old ones are dying, 

 some are damaged and must be speedily 



