82 HO WELL. [Vol. IV. 



colorless cell thus produced may change either into a nucleated 

 red corpuscle or into an ordinary marrow cell. According to 

 Obrastzow, the nucleated red corpuscles of most authors — 

 hasmatoblasts, according to his nomenclature — possess in the 

 living state no nucleus, the nuclear matter being diffused 

 throughout the cell. After the death of the cell, the nuclear 

 material becomes condensed to form a typical nucleus such as 

 is always described for the cell. The process of condensation 

 or separation of the nuclear matter resembles very much the 

 coagulation of blood, nuclear substance having properties 

 similar to though not identical with those of fibrin. The 

 transformation of the haematoblasts to red corpuscles consists 

 chiefly in the disappearance and absorption of the nuclear 

 matter. Obrastzow has seen in his preparations nucleated red 

 corpuscles, or hasmatoblasts, with the nuclei partially or com- 

 pletely extruded from the cell in the way described by Rind- 

 fleisch. He explains this, in accordance with his theory, as the 

 result of post-mortem changes brought about by the condensa- 

 tion of the protoplasm after death. Arndt also believes that 

 the nucleus of the nucleated red corpuscle does not exist in 

 the living cell, but is formed in consequence of post-mortem 

 changes. Indeed, he goes further than this and denies that 

 any nucleus is present in the living red corpuscles of the lower 

 vertebrates, — birds, reptiles, amphibia, etc. The apparent 

 nucleus so easily seen in these cells is caused by the action 

 of reagents or by post-mortem changes. The nucleus seen 

 in the nucleated red corpuscles after the death of the cell 

 consists histologically of a gelatinous ground substance con- 

 taining a number of granules. He speaks of these granules as 

 " elementary corpuscles," and thinks that they are of the same 

 nature as the granules found in protoplasm generally. 



Afonassiew (36) concludes that red corpuscles may be regen- 

 erated in three different ways: i. Nucleated red corpuscles 

 multiply by division and are finally changed to non-nucleated 

 red corpuscles. 2. The blood plates increase in size ; each 

 forms round itself an envelope of protoplasm in which haemo- 

 globin becomes developed, making a nucleated red corpuscle. 

 This loses its nucleus by extrusion and becomes an ordinary 

 red corpuscle. Under normal conditions this series of changes 

 takes place only in the marrow. He seems to think that the 



