THE CIRCULATING LIQUIDS OF THE BODY 17 



and envelopes or eats up substances, such as grains of carmine, 

 which come in its way. This kind of motion was first observed 

 in the amoeba, and is therefore called amoeboid. The leucocytes 

 of human blood are not all of the same size, and differ also in 

 other respects. They may be classified according to the presence 

 or absence of granules in their protoplasm, and the fineness or 

 coarseness of the granules ; according to the chemical nature 

 of the dyes with which the granules most readily stain, and 

 according to the form of the nucleus. Five varieties of leuco- 

 cytes may thus be distinguished in normal blood (Plate I.) : 



i. Polymorphonuclear Neutrophile Cells. The nucleus assumes a 

 great variety of forms, often contorted or deeply lobed, the lobes 

 being united by fine strands of chromatin. The protoplasm con- 

 tains numerous fine refractive granules, which stain best neither with 

 simple acid dyes like eosin nor with simple basic dyes like methylene 

 blue, but with mixtures which must be assumed to contain ' neutral ' 

 stains, like Ehrlich's so-called triacid stain.* These cells make up 



A - v. B. jS C. D. 



FIG. 2. AMCEBOID MOVEMENT. 

 A, B, C, D, successive changes in the form of an amoeba. 



65 to 75 per cent, of the total number of leucocytes. Their diameter 

 is 10 to 12 /j.. 



2. Eosinophile Cells (12 to 15 /* in diameter), much less numerous 

 in normal blood than the neutrophiles (less than 5 per cent, of the 

 whole), but found in considerable numbers in the serous cavities, 

 the connective tissue, and the bone-marrow. The granules in the 

 protoplasm are coarser than the neutrophile granules, and stain 

 much more deeply with eosin. The nucleus may be simple, lobed, 

 or even divided into fragments between which no connection can be 

 traced. It is less rich in chromatin, and stains less easily with basic 

 dyes, like methylene blue, than the nucleus of the first variety. 



3. Hyaline Cells, or Large Mononuclear Leucocytes, with a diameter 

 of 12 to 15 fji. They possess a large simple nucleus, poor in chromatin, 

 surrounded by a relatively great amount of protoplasm, with no 

 evident granules. They constitute 3 to 5 per cent, of the total 

 number of leucocytes. 



4. Lymphocytes. Smaller cells than any of the preceding (diameter 

 6 /*), possessing a single large nucleus, surrounded by a comparatively 

 small amount of protoplasm ; 20 to 25 per cent, of the leucocytes of 

 the blood belong to this group. 



* A mixture of orange G., acid fuchsin, and methyl green. 



2 



