224 NORMAL AND PATHOLOGICAL BLOOD 



Normoblasts 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 leukancemia 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 a 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 imperceptibly 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 large mononu- 

 clear. The difficulty is even greater when we deal with Tiirck's irritation forms and 

 with myelocytes. 



Without going into the various granule stainings so thoroughly brought 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 us information not yielded by either haematoxylin and 

 eosin or the triacid, the points of differentiation to be referred to in that which 

 follows is with blood so stained. 



In considering the staining affinities of different parts of the leuko- 

 cytes, it is convenient to divide such into basic ones, acid ones, and 

 those which may be said to be on the border line between these the 

 so-called neutrophilic affinities. 



With Wright's stain we have the eosinophile or oxyphile affinity of the 

 granules of eosinophiles for acid dyes, in this case eosin. The nuclei and baso- 





