BLOOD 221 



amebse. As a result of this ameboid movement they 

 assume a different shape from time to time. White 

 cells have the properties of moving about and coming 

 in contact with bacteria, and disintegrated tissues, then 

 can be seen taking them into their substance and elimi- 

 nating them from the cell or digesting the invader. 

 They can by their movements slip through the wall 

 of the capillary vessel and appear in the adjacent 

 lymph spaces. This power of the white cell is best 

 appreciated in the early stages of inflammation when 

 the blood stream is always engorged with red and white 

 corpuscles; the latter can be seen passing into, through, 

 and outside the wall, and preparing to combat the 

 invading gerrn causing the trouble. This action of 

 the white corpuscles is called diapedesis. 



The large and small lymphocytes originate in the 

 lymph glands, the solitary and combined glands of 

 the intestines, etc. They are carried into the blood 

 stream from these glands by means of the flowing 

 lymph. The polymorphonuclear, eosinophiles, baso- 

 philes, and leukocytes are derived from the bone- 

 marrow only. They reach the circulation by entering 

 the capillaries in the bone-marrow. Leukocytes dis- 

 appear by a process of dissolution. The period of 

 their life is unknown. 



Function of White Cells. The polymorphonuclear, 

 large and small, lymphocytes possess the properties 

 of engaging and removing bacteria and broken-down 

 tissue. They attack and destroy more or less effec- 

 tively forms of intruding bacteria by surrounding, 

 and incorporating the tissue or bacterium and elimi- 

 nating them by a process of digestion. This swallowing 

 action of these white cells caused Professor Metchni- 

 koff to call them phagocytes, and the process as phago- 

 cytosis. Thus these scavengers aid the human body 

 in recovering from disease by combating and destroy- 

 ing the invading bacterium. White cells are supposed, 

 after breaking up, to contribute certain protein 



