The Physiological Destruction of Erythrocytes in Birds. 547 



first marked change in the erythrocyte is an hemolysis, the hemo- 

 globin escaping into vacuoles of the cytoplasm of the phagocytic cell 

 and leaving the nucleus- containing stroma distinctly outlined (Fig. 2, 

 a and b). The stroma may retain the original ovoid form or may 

 become spherical, the nucleus in each instance remaining ovoid. 

 Gradually, both the stroma and nucleus lose their staining reaction 

 (Fig. 2, a and b) until finally, the vacuole contracts about a small 

 indistinct remnant of the nucleus which in its turn ultimately dis- 

 appears. With this change, the bulk of the hemophage decreases (Figs. 3 

 and 4, c). Meanwhile, the hemoglobin which has escaped into the cyto- 

 plasm of the hemophage, is seen to undergo a series of changes. At 

 first the greater part of the pigment does not give the iron reaction 

 but retains its yellow-bronze tone with erythrosin and occupies vacuoles 

 of various sizes (Fig. 4, d). In hemophages representing a later stage 

 however, the contents of the vacuoles give the iron reaction also and 

 with great intensity, contrasting with the lighter blue of the sur- 

 rounding cytoplasm. Such cells show no content of unmodified hemo- 

 globin. With the disappearance of the native hemoglobin therefore, 

 there is a parallel increase in the iron-reacting pigment. The con- 

 tent of the vacuoles which gives the iron reaction appears in untre- 

 ated specimens, as a golden -yellow pigment and is presumably 

 hemosiderin. The hemophages which represent the last stages 

 in the phagocytosis and digestion, appear less and less bulky, with 

 a fainter iron reaction, and a less vesicular nucleus (Figs. 3 and 

 4, c). The last observable stage is represented by a cell which 

 contains no yellow pigment but which in all ways appears as 

 a typical endo thelial cell of the vascular intima except however, 

 that its cytoplasm gives a faint and diffuse iron reaction (Fig. 

 Le): 



As stated above examples of the stages just outlined are readily 

 seen in a single microscopic field and the interpretation of the sequence 

 of events which they represent, leads to the conclusion that the cells 

 of the vascular endothelium of the venous capillaries of the liver of 

 birds in performing a normal physiological function, ingest intact red 



blood-corpuscles, hémolyse the same, destroy the stroma and nucleus, 



35* 



