2 54 TEXT-BOOK OF PHYSIOLOGY. 



HISTOLOGY OF THE WHITE CORPUSCLES OR LEUKOCYTES. 



The histologic features of the white corpuscles can readily be 

 observed under the same conditions as in the case of the red corpuscles. 

 Within the smaller blood-vessels they are seen adhering to the walls 

 oLthe vessel; in a drop of freshly drawn blood they are founcTiif the 

 spaces between the rouleaux of red corpuscles, (See Fig. 96, p. 236.) 



Shape and Size. In the resting condition, whether seen in the 

 vessel or on the stage of the microscope, the white corpuscle, as its 

 name implies, is grayish in color, round or globular in form, though 

 often presenting a more or less irregular surface, its diameter varies 

 from 0.0004 to 0.0013 mm., though the average is about o.ooii mm. 

 or about -^Vn- inch. 



Structure. A typical \vhite corpuscle consists of a ground- 

 substance uniformly transparent and apparently homogeneous, in 

 which are embedded a number of granules of varying size, some of 

 which are very fine, while others are larger. By various reagents it 

 has been demonstrated that the granules are fatty, proteid, and 

 carbohydrate (glycogen) in character. In the fresh cells the ex- 

 istence of a nucleus is difficult of detection, though its presence can 

 be demonstrated by the addition of acetic acid, which renders the 

 perinuclear cytoplasm more transparent and makes the nucleus 

 conspicuous and sharply defined. From its structure it is apparent 

 that the white corpuscle belongs to the group of undifferentiated 

 tissues and resembles the cells of the embryo in its earliest stages as 

 well as the unicellular organism, the amoeba. 



Number of White Corpuscles. The number of white cor- 

 puscles per cubic millimeter of blood is much less than the number r 

 of red corpuscles, the ratio being in the neighborhood oKi white to 

 700 red^ This ratio, however, varies within wide limits in different 

 portions of the body and under normal variations in physiologic 

 conditions. In the blood of the splenic artery there is but i white 

 to 2260 red, while in the splenic vein there is i white to every 60 red; 

 or about thirty-eight times as many as in the artery. In the portal 

 vein there is i white to 740 red, while in the hepatic vein there is i 

 white to 170 red. 



JThe total number of white corpuscles per cubic millimeter has 

 n estimated at from 5000 to 10,000, though the average is about 

 7500. j| The number, however, is influenced by a variety of physio- 

 logic conditions. The ingestion of food rich in proteid material 

 raises the count from 30 to 40 per cent., as compared with the 

 count before the meal. Fasting for a few days always lowers the 

 count, and in a case of total abstinence of food for a week, reported 

 by Luciani, the count fell to 86 1 per cubic millimeter, after which 

 it rose to 1530, where it practically remained for the succeeding three 



