Wounds and Surgical Diseases 77 



of pus and blood poisoning. We have seen 

 in the first chapter that although most of the 

 cells of the body have assumed special forms 

 and powers as the body develops out of its 

 embryonic period, there are some cells which 

 scarcely seem to have got beyond the stage 

 in which the simplest of the unicellular 

 organisms, such as the amoeba, belong. The 

 most prominent of these lowly organized cells 

 in the body are the white blood-cells or, 

 leucocytes as they are called. (See Plate XL) 

 Under ordinary conditions these go circling 

 round in the blood-vessels along with the red 

 blood-cells, or, crawling out of the blood- 

 vessels, slowly make their way about in the 

 smaller spaces in the tissues. All the things 

 they do under these circumstances we do 

 not know. But they are at any rate the 

 great scavengers of the body. When they 

 come across a particle of worn-out or foreign 

 material in the tissues, they take it into 

 themselves, just as amoeba does its food in 

 water, and either digest it or carry it back 

 to those parts of the body in which waste 

 material is systematically disposed of. 



