BLOOD. 47 



and thereby stimulates the erythroblastic cells to more rapid multiplication. 

 Iu the case of a diminution in oxygen-pressure, as happens when the altitude 

 is markedly increased, we may suppose that one result is again a slight dimi- 

 nution in the oxygen-supply to the tissues, including the red marrow, and in 

 consequence the erythroblasts are again stimulated to greater activity. This 

 variation in haemoglobin with the altitude is an interesting adaptation which 

 ensures always a normal oxygen-capacity for the blood. 



Physiolog-y of the Blood-leucocytes. — The function of the blood-leuco- 

 cytes has been the subject of numerous investigations, particularly in connection 

 with the pathology of blood diseases. Although many hypotheses have been 

 made as the result of this work, it cannot be said that we possess any positive 

 information as to the normal function of these cells in the body. It must be 

 borne in mind in the first place that the blood-leucocytes are not all the same 

 histologically, and it may be that their functions are as diverse as is their mor- 

 phology. Various classifications have been made, based upon one or another 

 difference in microscopic structure and reaction. Thus, Ehrlich groups the leuco- 



b 



Fig. 7.— Blood stained with Ehrlich's "triple stain" of acid-fuchsin, methyl-green, and orange G. 

 (drawn with the camera lucida from normal blood) (after Osier): a, red corpuscles; b, lymphocytes; c, 

 large mononuclear leucocytes; <l, transitional forms; >, neutrophilic leucocytes with polymorphous 

 nuclei (polynuclear neutrophiles) ; /, eosinophilic leucocytes. 



cytes according to the size, the solubility, and the staining of the granules 

 (contained in the cytoplasm, making in the latter respect three main groups; 

 oxyphiles or eo&inophiles, those whose granules stain only with acid aniline 

 dyes — that is, with dyes in which the acid part of the dye acts as the stain ; 

 basophiles, those which stain only with basic- dyes; and neutrophiles, those 

 which stain only with neutral dyes 1 (Fig. 7). This classification is fre- 

 quently used, especially in pathological literature, but it is not altogether 

 satisfactory, since no definite functional relationship of the granules has been 

 established ; and, moreover, it is undecided whether or not the granules arc 

 permanent or temporary structures in the cells. A simpler classification 



1 Ehrlich : Die Ancemie, Vienna, 1S98; Kanthack and Hardy, Journal of Physiology, vol., 

 xvii., 1894, p. 81. 



