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Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.
 
the structure of the erythrocytes. The older view, that of Rollett, supposes that the corpuscle consists of a sponge work or stroma permeated by a solution of hemoglobin. Schäfer, on the other hand, believes that the hemoglobin solution is contained within an envelope or membrane, and the facts stated above with regard to the osmotic behavior of the erythrocyte support this belief. The envelope consists mainly of lecithin, cholesterin, and nucleoprotein.
  The colorless corpuscles or leucocytes are of various sizes, some no larger, others smaller, than the red corpuscles, In human blood, however, the majority are rather larger than the red corpuscles, and measure about 10μ in diameter. On the average from 7000 to 12,000 leucocytes are found in each cubic millimetre of blood.


FIG. 454– Varieties of leucocytes found in human blood. Highly magnified. (See enlarged image)

  They consist of minute masses of nucleated protoplasm, and exhibit several varieties, which are differentiated from each other chiefly by the occurrence or non-occurrence of granules in their protoplasm, and by the staining reactions of these granules when present (Fig. 454). (1) The most numerous (60 per cent.) and important are irregular in shape, possessed of the power of ameboid movement, and are characterized by nuclei which often consist of two or three parts (multipartite) connected together by fine threads of chromatin. The protoplasm is clear, and contains a number of very fine granules, which stain with acid dyes, such as eosin, or with neutral dyes, and are therefore called oxyphil or neutrophil (Fig. 454, P). These cells are termed the polymorphonuclear leucocytes. (2) A second variety comprises from 1 to 4 per cent. of the leucocytes; they are larger than the previous kind, and are made up of coarsely granular protoplasm, the granules being highly refractile and grouped around single nuclei of horse-shoe shape (Fig. 454, E). The granules stain deeply with eosin, and the cells are therefore often termed eosinophil corpuscles. (3) The third variety is called the hyaline cell or macrocyte (Fig. 454, H). This is usually about the same size as the eosinophil cell, and, when at rest, is spherical in shape and contains a single round or oval nucleus. The protoplasm is free from granules, but is not quite transparent, having the appearance of ground glass. (4) The fourth kind of colorless corpuscle is designated the lymphocyte (Fig. 454, L), because it is identical with the cell derived from the lymph glands or other lymphoid tissue. It is the smallest of the leucocytes, and consists chiefly of a spheroidal nucleus with a very little surrounding protoplasm of a homogeneous nature; it is regarded as the immature form of the

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