COMPOSITION OF THE BLOOD 345 



hematoUasts. These cells are invariably present in the red bone-marrow of 

 the flat bones, of the stermim and of the ribs, the base of the skull and the 

 vertebrae. The red blood cells which at first contain a nucleus, lose this later 

 by caryolysis, ■ i. e., by dissolution of the nucleus (according to some investi- 

 gating authors by expulsion) and then enter the circulating blood as non- 

 nucleated red blood-discs. We must at present adhere to the view that in 

 post-fetal life the red (non-nucleated) blood cells are formed exclusively in 

 the red hone-marrow, namely, from the nucleus-containing, red blood cells 

 which are constantly present in these regions. The latter cells, the hemato- 

 blasts, appear, at least in embryonic life, to arise from lymphocytes by hemo- 

 globin production, first as megaloblasts, which perhaps are originally the 

 mother cells of the normoblasts. [Several authorities of the first rank take 

 exception to this account of the hematoblasts, and believe that red and white 

 cells arise from difEerent stems. — Ed.] However, after the latter have been 

 formed, they increase by mitosis, constantly producing new normoblasts. Be- 

 sides the bone-marrow, in embryonic life the lymph-glands also probably have 

 an erythropoietic function [probably also the liver, and possibly the spleen. — 

 Ed.] ; but in the adult organism blood-formation occurs only in the bone- 

 marrow, where also the transformation of normoblasts into non-nucleated blood 

 discs occurs (by caryolysis). Under normal conditions only non-nucleated 

 blood cells pass from the bone-marrow into the blood. Whenever an appre- 

 ciable quantity of nucleated red blood cells is found in the blood, pathological 

 conditions are present: Infections, intoxications, inanition. If large num- 

 bers of nucleated blood cells are in circulation, severe anemias, even of the 

 severest character, are present. 



When the red blood cells die they are replaced by fresh material coming 

 from the bone-marrow, so that the number of erythrocytes remains at almost 

 a constant figure, namely, about 5,000,000 for men and about 4,500,000 for 

 women ta the cubic millimeter, a proportion of about 600 to 1 of the white cells 

 [5,000,000 is too low for the average of healthy adult males in America. The 

 correct figure is much nearer 6,000,000. — Ed.] The majority of the blood 

 cells, unquestionably, disintegrate in the liver. We are justified in this as- 

 sumption for reasons which need not be here minutely considered, and of 

 which oTaly one shall be mentioned, viz., that in the liver large amounts of 

 biliary coloring matter are daily produced. But bile, as its chemical compo- 

 sition proves (hematin CgaHg^N^O^Fe by taking up water and giving off iron— 

 + 2H2O - Fe— forms bilirubin CjjHselSr.Oe), can only consist of hemoglobin 

 which has been given up from the stroma of the red blood cells. We can in 

 fact artificially increase at will the production of biliary coloring matter by 

 the injection of hemoglobin into the blood. 



The white blood cells (leukocytes) represent colorless, membraneless cells 

 with one or more nuclei and a protoplasm variously constituted. Since the 

 introduction of new methods of staining in examining the blood, the first 

 application and completion of which we owe to P. Ehrlich's excellent investi- 

 gations in the pathology of the blood, the fact has developed that normal blood 

 contains not only two varieties of leukocytes, as was assumed for a long time, 

 but many kinds, differing markedly from each other. .It is best to differen- 



