I QO NORMAL AND PATHOLOGICAL BLOOD 



stead of being round, the nucleus is irregular and may be trefoil in shape. 

 The cytoplasm surrounding the nucleus shows polychromatophilia. 

 This contrasted with the pure blue of the lymphocytes should differen- 

 tiate. Nornioblasts are found in secondary anaemias, and especially in 

 myelogenous leukaemia. Megaloblasts are peculiarly characteristic of 

 pernicious anaemia. Enormous megaloblasts are sometimes termed 

 gigantoblasts. 



In aplastic anaemia (a severe type of pernicious anaemia), in contrast to ordinary 

 pernicious anaemia, nucleated reds are very rarely found. There is also very little 

 poikilocytosis, and the color index is about normal. It is a rare, rapidly fatal 

 anaemia, particularly of young women. 



It does not show remissions, runs a rapid course, and is attended with a marked 

 increase of lymphocytes. The bone marrow of the femur is pinkish yellow and 

 homogeneous. 



The term leukanaemia has been employed to describe conditions 

 which partake of the characteristics of pernicious anaemia and leukaemia. 



WHITE CELLS. 



Owing to the conflicting views as to origin, nature, and functions of 

 the various leukocytes, their classification is in a state of confusion. 

 As regards the appearance of the cells, this of course varies as the stain 

 used, and it requires considerable experience for a single individual to be 

 able to positively recognize the difference between a lymphocyte and 

 a large mononuclear when one specimen is stained with a Romanowsky 

 stain, another with Ehrlich's triacid, and a third with haematoxylin and 

 eosin. This, of course, is intensified when different persons adhere to 

 the method of staining which they prefer and are at a loss to appreciate 

 differences which are brought out by some other stain used by some 

 other person. Even with the same stain used with different specimens 

 of blood we find the staining characteristics of various leukocytes imper- 

 ceptibly merging the one into the other, so that at times it is impossible 

 for one, even with his own standard of differentiation, to be sure whether 

 he is dealing with a lymphocyte or a laige mononurlear. The difficulty 

 is even greater when we deal with Turck's irritation forms and with 

 myelocytes. 



Without going into the various granule stainings so thoroughly 

 brough out by Ehrlich, we shall immediately take up the question of 

 a practical classification for use in making a differential count. As the 

 Romanowsky method of staining (Wright, Leishman, or Giemsa) gives 



