THE WHITE BLOOD-CELLS. 221 



Red. White. 



Hepatic vein, . 170 1 



Portal vein, .... ... 7401 



According to age or sex : 



Girls, 4051 



Boys, 2261 



Adult, 3341 



Old age, 3811 



According to general conditions : 



When fasting, 7161 



After meal, 3471 



During pregnancy, 281 1 



In a disease of the spleen and lymphatic glands called Leuco- 

 cythemia there may appear to be nearly as many white cells as 

 red disks. Here, however, the red disks are deficient, while the 

 colorless cells are multipled. 



THE WHITE BLOOD-CELLS. 



The protoplasmic cells of the blood, commonly called the white 

 corpuscles, differ in no essential respect from the pale round cells 

 which are found in most of the tissues of the body. They exist 

 in great numbers in the fluid which drains back from the tissues 

 into the blood, namely, the lymph, and occupy a great part 

 of the lymphatic glands and spleen. They are often spoken of 

 as lymphoid cells, leucocytes, or indifferent formative cells, on ac- 

 count of their being so widely distributed throughout the tissues. 



When fresh blood is examined with the microscope these cells 

 can be seen generally adhering to the glass slide or cover-glass 

 and lying singly, apart from the groups of red disks. They can 

 be recognized by their faintly bluish hue or absence of marked 

 color, their finely granular structure, spherical shape, and the 

 nuclei which may often be recognized near the centre of the cell. 

 Though not always visible in quite fresh preparations, the nuclei 

 can be brought to light by the action of many reagents e.g., 

 acetic acid. If looked at while being moved by the blood-cur- 

 rent in the capillary vessels, they are seen to pass slowly along 

 in contact with the vessel wall, while the red corpuscles rush rap- 



