COMPOSITION OF THE BLOOD 347 



The normal percentage of polynuclear leukocytes is in this country more 

 often near 60 per cent, than near 70 per cent.— Ed.] 



2. Eosinophile cells, characterized by their size and by the coarse granules 

 in their protoplasm which stain intensely by acid stains (eosin). [The size of 

 eosinophiles is not characteristic. They are about the size of a polynuclear 

 cell or often a little smaller, but their irregular shape (as seen in thin smear 

 preparations) renders a definite statement as to their diameter difficult. — 

 Ed.] They resemble the neutrophilic polynuclear cells and, like these, are 

 markedly contractile ; their number amounts to about 3 per cent, of the white 

 blood-corpuscles. 



3. Basophilic leukocytes, " mast-cells " are scanty in normal blood (0.5 

 per cent, of the leukocytes). They are characterized by the intense basophilic 

 reaction of the granules in their protoplasm and by the very slight staining 

 affinities of the nucleus ; the granulation does not color with the triaeid stain, 

 hence mast-cells appear in triaeid preparations as light, non-granular cells. 



Opinions are more at variance concerning the origin of the white blood- 

 corpuscles than of the red, although a number of investigators (Virchow, 

 Kolliker, Max Schultze, Neumann, Heidenhain, Arnold, MokofE, Eieder, 

 Engel and, above all, P. Ehrlieh, and in late years Askanazy, Pappenheim and 

 Eubenstein) have closely studied this subject. At present, it is difficult, almost 

 impossible, to take a positive stand in the mooted question. The following 

 theory is probably more in accordance with present opinions than any other. 



After the investigations of the last decade, and especially since the intro- 

 duction of tinctorial methods of examination by Ehrlieh, Virchow's view that 

 the lymphocytes are the young, the leukocytes the old, forms of the cells, the 

 latter arising from the former, can no longer be accepted in its simple, strict 

 conception. On the contrary, it is better to adhere to the view that the lympho- 

 cytes, the leukocytes and the hemaglobin-containing cells represent separate 

 stages of development of cells, which probably are only alike in their first 

 elements — namely, cells with non-granular, weakly basophilic protoplasm and 

 one round nucleus. From these the myelocytes develop in the lone-marrow, 

 the protoplasm becoming granular (neutrophilic or eosinophilic), while the 

 nucleus still retains its round form; in the later stages of development the 

 granulation becomes more marked, the nucleus flattened, sinuate and, finally, 

 pigmented (polymorphonuclear leukocytes with neutrophilic or eosinophilic 

 reaction). At this age the cells enter the circulating blood as "polynuclear" 

 leukocytes. A few immature cells, i. e., still basophilic, non-granular and sup- 

 plied with one nucleus, enter the blood as the so-called " mononuclear " leuko- 

 cytes, which then mature in the blood, becoming polynuclear leukocytes. The 

 cells which have begun to mature in the bone-marrow remain in the bone- 

 marrow until perfectly mature, becoming polynuclear leukocytes, so that the 

 blopd does not normally contain myelocytes. The mature polynuclear cells, 

 however, enter the blood upon chemotactic, physiological irritation in rela- 

 tively small but usually quite constant numbers, under pathological condi- 

 tions frequently in very large numbers ("leukocytosis"). The loss of the 

 polynuclear cells which pass into the blood is compensated by the for- 

 mation of new primary stages of the same, the myelocytes, and by the fur- 



