THE BLOOD AND THE BLOOD-FORMING ORGANS. 377 



form of small granules occupying the cell body and staining more deeply 

 with methylene blue than do normal cells (granular degeneration). 



It should be remembered that during the manipulations required in 

 making dried specimens the red cells may suffer a variety of artificial 

 changes, many of which are very confusing. 



Nucleated red blood cett$ are found in the blood in all forms of anemia, 

 and their appearance indicates regenerative activity on the part of the 

 Their presence in the Mood, though at all 



periods of extra-uterine life abnormal, may usually be regarded as of 

 favorable import in disease. Within a few hours after severe hemor- 

 rhage nucleated red cells may be noted in considerable numbers. ' Dur- 

 ing the regeneration of the blood in anaemia, the occurrence of nucleated 

 red cells is nearly constant, but subject to rather sudden periodical vari- 

 ations sometimes called "blood crises." In favorable cases of anemia 

 nucleated red cells of normal size only (normoblasts) (Plate II. , Figs. 

 2 and 3) are seen, whose compact, darkly staining nucleus may be found 

 either in the centre of the cell or slightly protruding from the periphery ; 

 or, nuclei apparently quite extruded from the cell may be found free in 

 the plasma. 



In severe anaemia attended with an abnormal type of blood formation, 

 very large nucleated red cells (megaloblasts} (Plate II., Fig. 4) appear 

 in varying numbers. The protoplasm of these cells often shows an ex- 

 cess of hemoglobin, but frequently the purple stain produced by a com- 

 bination of the eosin and methylene blue indicates an altered form of 

 hemoglobin, or very fine basophile granules may be demonstrated by 

 treatment with methylene blue. The nuclei of the megaloblasts may be 

 single and compact, or a single large nucleus may show stages of direct 

 division, or in extremely large cells {gigantoblasts} the nuclei may present 

 phases of mitosis. 



ALTERATIONS IN THE WHITE BLOOD CELLSo 



V. -* 



THE LEUCOCYTES OF NORMAL BLOOD. 



The leucocytes of normal blood may be classified according to their 

 place of origin, or by the character of their nuclei, or by the reac- 

 tion of the granules in their protoplasm to certain dyes. The most ser- 

 viceable classification is that based both upon the character of the nucleus 

 and upon the reaction of the protoplasm to dyes, according to which we 

 may distinguish in normal blood the following forms (see Plate II., 

 Fig. 1): 



1. ^LYMPHOCYTES, smalljeucocyjes of afcont the size of red cells or, 

 larger] with asingle compact, deeply staimngjmcleus, surrounded bya 



1 The appearance of nucleated red cells and abnormal forms has been frequently 

 noted in those who have recently arrived in mountainous regions, the probable explana- 

 tion being that the lowered oxygen tension of the rarefied air demands a larger amount 

 of hemoglobin to supply the wants of the tissues, with the result that for a short time 

 immature red cells are set free from the bone marrow. 



