DIFFERENTIAL LEUCOCYTE COUNT 215 



its staining reactions, stains with the basic stain to a greater or 

 less extent ; thus, with Jenner's stain it stains a variable mixture 

 of pink (from the eosin) and blue (from the methylene blue). It 

 may be hlac, purplish, or almost pure blue. The change is 

 readily recognisable in ordinary films stained by Jenner's method. 



It is especially common in pernicious anaemia and in von 

 Jaksch's anaemia of children, but may occur in almost any form 

 of anaemia, if very severe. It is not a very important diagnostic 

 feature, but its presence always constitutes a bad sign. 



5. Granular degeneration (Plate VIII., Fig. 2) takes the form of 

 numerous granules of varying size, which occur in the red cor- 

 puscles, and which stain almost black with the basic portion of 

 the stain ; the rest of the corpuscle often shows polychromatophil 

 degeneration. 



It occurs also in any severe anaemia, especially in von Jaksch's 

 ansemia, where corpuscles in which it occurs may be extremely 

 plentiful. Except where this occurs it is not of much diagnostic 

 importance, unless it is true that it occurs as a very early and 

 constant sign in lead-poisoning. 



Nucleated Forms (-blasts). 



I. Normoblasts (Plate VIII., Figs. 7, 8, 9). — -These are corpuscles 

 which resemble the normal in shape and size, but which have a 

 nucleus. This is central, large in proportion to the corpuscles, 

 surrounded by a comparatively narrow band of stroma, and 

 circular; in some cases it is double or multiple. Normoblasts can 

 usually be recognised with ease from any other cells which occur in 

 the blood, from the fact that the nucleus stains very deeply — more 

 deeply than any other found in the blood. It frequently happens 

 that the narrow ring of stroma may show polychromatophil de- 

 generation and stain blue ; in this case it is difficult to distinguish 

 the cell from a lymphocyte, but the deeply stained, almost black, 

 nucleus should prevent mistakes. 



Normoblasts are the cells from which the normal blood- 

 corpuscles are formed, but in health they are confined to the 

 bone-marrow, except in very young infants, in whom a very few 

 may be found in the circulation. Their presence in the blood of 

 older persons indicates an anaemia of some severity, and that this 

 anaemia is being combated in a normal way ; the bone-marrow is 

 so active that some of its normoblasts overflow into the circulating 

 blood. They are therefore rather a good sign than otherwise. 



