WILD CREATURES OF GARDEN AND HEDGEROW 



blood there are two kinds of minute organisms, 

 the one red, called the red corpuscles, which 

 give the crimson colour we know so well, and 

 the other white, and known as the white 

 corpuscles. These latter act like soldiers and 

 defend the body from germs. They fall upon 

 the invaders and practically speaking eat them 

 up. All day and every day the fight goes on ; 

 when we are ill the defending army has got the 

 worst of it, when we get better it has conquered. 

 These corpuscles are exceedingly tiny, and at 

 ordinary times there will be as many as eighteen 

 thousand to twenty thousand per cubic milli- 

 metre (a millimetre is the twenty- fifth of an 

 inch) in the blood of a hedgehog. At the be- 

 ginning of hibernation a great change takes 

 place only about one thousand to three 

 thousand white corpuscles remain per cubic 

 millimetre ; they have invaded the tissues of 

 the stomach, there to destroy the bacteria of 

 purification that have been brought in with 

 its food, which otherwise could pass into the 

 blood and destroy the animal. As soon as this 

 work is done they are absorbed and disappear. 

 In the meantime the blood has been reacquir- 

 ing its normal number of corpuscles. 1 



1 G. E. H. Barrett-Hamilton, A History of British Mammals, p. 65. 

 280 



