THE COLORLESS CORPUSCLES OR LEUCOCYTES 113 



cells during the later months. This does not begin until after the third 

 month, and is most marked and constant in primiparse. After parturition 

 the leucocytes gradually diminish under normal conditions, and usually 

 reach the normal within a fortnight. The essential factor is probably the 

 general stimulation in the maternal organism. It is well established that the 

 white cells are very numerous in the new-born, though different observers 

 have made very conflicting estimates. Still all agree that there is a very 

 rapid decrease in their numbers during the first few days, and that this is 

 followed by a less marked increase, which continues for many months. 

 According to Rieder, who is perhaps the most reliable, there are at birth 

 from 14,200 to 27,400 per cubic millimeter, and after the fourth day from 

 12,400 to 14,800. 



Varieties of Leucocytes, The colorless corpuscles present greater diversi- 

 ties of form than the red ones, plate II. They are usually classified according 

 to their reaction to staining agents, or to the presence or absence of granules 

 in their cytoplasm. Kanthack and Hardy offer the following classification, 

 based upon both phenomena: 



Leucocytes. 



A. Oxyphile (staining with acid dyes). . . J 1 ' Finel > r granular. 



| 2. Coarsely granular eosmopmle. 



B. Basophile (staining with basic dyes) . . i. Finely granular. 



C. Hyaline .. . . J T ' Sma11 lymphocyte. 



( 2. Large myelocyte. 



The finely granular oxyphile constitutes 75 per cent of all leucocytes. 

 It has an average diameter of 10 ^it, and possesses phagocytic action to a 

 marked degree that is, it possesses the power of ingesting foreign particles. 

 Its nucleus consists of several lobes united by threads of chromatin. This 

 cell was formerly known under the term neutrophile, because of its supposed 

 reaction to neutral dyes. 



The coarsely granular form of eosinophile constitutes only 2 per cent of 

 the leucocytes. It has a diameter of 12 p, and a reniform nucleus. 



The basophile cell is rarely found in normal blood. It may occur occa- 

 sionally during periods of digestion. It is a small, spherical cell, with an 

 irregular nucleus and a diameter of 7 p,. 



The small hyaline leucocyte is also called a lymphocyte, because of the 

 large numbers found in adenoid tissue, and is supposed to be an immature 

 form. The nucleus is proportionally large, and is surrounded by but little 

 protoplasm in which no granules can be detected. The cell is about the 

 size of a red blood-cell, and constitutes from 10 to 20 per cent of all leucocytes. 



The large hyaline or myelocyte varies in diameter from 8.5 to 10 p,. Its 

 nucleus is spherical or reniform, and is surrounded by more protoplasm than 

 in the case of the lymphocyte. It forms about 10 per cent of the leucocytes. 



Ameboid Movement of Leucocytes. The remarkable property of the color- 

 8 



