132 



NORMAL HISTOLOGY. 



particles in the tissues, and thus act as scavengers. This activity 

 has been called their phagocytic function, and may play an impor- 

 tant part in the removal of material that should be absorbed or of 

 particles that would otherwise be injurious to the tissues ; e. </., 

 bacteria. (See statements regarding the nature of colostrum-cor- 

 puscles.) 



The emigration of leucocytes from the bloodvessels is pronounced 

 in many of the inflammatory processes, and their phagocytic func- 

 tion may have a marked influence on the result. 



The leucocytes are produced in the lymphadenoid tissues of the 

 body, the lymphatic glands, thymus, spleen, and the more diffusely 

 arranged tissues of like structure, but probably most abundantly in 

 the red marrow of the bones. 



A close study of the leucocytes has resulted in their subdivision 

 into a number of groups according to their morphological differences 



Fig. 113. 



Leucocytes from normal human blood. (Biihm and Davidoff.) a, red blood-corpuscle, intro- 

 duced for comparison; b, small mononuclear leucocyte (lymphocyte); c, large mono- 

 nuclear leucocyte ; g, polynuclear leucocyte. These differ in the character of the granules 

 they contain (not represented in the figure). In normal blood those granules are neutro- 

 philic in the vast majority of the polynucleated leucocytes. Occasionally they are acido- 

 philic, " esinophile leucocytes"; sometimes basophilic, " mast-cells " or "plasma-cells." 

 d, e,f, intermediate and probably transitional forms between the large mononuclear leu- 

 cocytes c, and the polynucleated leucocytes, or leucocytes with polymorphic nuclei, g. 



or to peculiarities in their behavior toward coloring-matters. The 

 best defined of these groups are : 



1. The polynuclear neutrophilic leucocytes, in which the nucleus 

 has a very irregular form, often presenting the appearance of two 

 or more nuclei, and the cytoplasm contains granules that have an 



