MICROSCOPIC STRUCTURE OF THE BLOOD. 289 



increase in the number of leukocytes in the blood, together with 

 enlargement and proliferation of the lymphoid tissue of the 

 spleen, lymphatic glands, and bone-marrow. The disease is 

 distinguished as lymphatic, splenic, lymphaticosplenic, medullary or 

 myelogenic, and lienomyelogenous, according as the disease involves 

 the lymphatics, the spleen, both the spleen and the lymphatics, 

 the bone-marrow, or both the spleen and bone-marrow. It may 

 be due to disorder of the intestines (intestinal leukemia), of the 

 liver (hepatic leukemia), or to disease of the tonsils (amygdaline 

 leukemia) Borland's Medical Dictionary. 



If peptones or leech extract are injected into the blood-vessels, 

 there is at first a diminution in the number of the leukocytes, 

 especially the poly nuclear variety ; this is termed the leukocyto- 

 penic phase; afterward the number is increased, constituting the 

 leukocytotic phase. 



Acute local inflammation causes similar changes as do these 

 injections, but the diminution in the number of leukocytes in this 

 case largely affects the coarsely granular variety, while the after- 

 increase is found mainly in the finely granular corpuscles (Schafer). 

 It has been observed that the blood clots more readily when the 

 coarsely granular cells are relatively few in number, and Schafer 

 thinks this may explain the more ready clotting of blood in in- 

 flammatory conditions. 



Varieties of Colorless Corpuscles. Ehrlich classifies the color- 

 less cells according to the kind of anilin stain which the majority 

 of the contained granules take ; thus cells whose granules are 

 stained by basic dyes, as methylene-blue, he terms basophil ; 

 while those whose granules are stained by acid dyes, such.as eosin, 

 he calls oxyphil or eosinophil. These terms are also written 

 basophile, oxyphile, and eosinophile. 



Still another classification divides the colorless corpuscles into 



(1) lymphocytes, which are characterized by being small, having a 

 round vesicular nucleus, and named from their resemblance to the 

 leukocytes of lymph-glands, but not possessing ameboid movement; 



(2) mononuclear leukocytes, cells with a single nucleus ; and (3) 

 polymorphous or polynucleated leukocytes, characterized by having 

 more than one nucleus or else a divided nucleus, the divisions 

 being connected by protoplasm. Nos. 2 and 3 possess ameboid 

 movement. It is believed by some authorities (Howell) that these 

 varieties are simply different stages in the development of a single 

 type of cell, the lymphocytes being the youngest and the polynu- 

 cleated leukocytes the oldest. The granules of the mononuclear 

 variety are coarser and stain more deeply with eosin than do those 

 of the polynuclear, but constitute only about 5 per cent, of the 

 total colorless corpuscles ; while the basophil cells are not often 

 found. Still another variety, called hyalin, is described ; these 

 have no granules. It should be borne in mind that it is the kind 



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