442 WILLIAM H. F. ADDISON 



cytes are present in about the same numbers as before. The 

 splenocytes contain brown masses derived from the ingested 

 particles of blood. These may exist as a single large mass in a 

 cell or as many small ones. The average size of the splenocytes 

 has not increased to any extent. 



Four and one-half hours. Fragments of the injected pigeon 

 corpuscles are still abundant, intermingled with the rabbit cor- 

 puscles. The polymorphonuclears have increased in number and 

 myelocytes are frequent. The splenocytes may contain a single 

 brownish mass, or more frequently many inclusions, usually 

 brownish globules and often leucocytes. One cell was seen 

 containing seven polymorphonuclears, as well as many fine brown 

 dots. The average size of five splenocytes was 16.7 X 10.8 n, 

 with nucleus 6.8 X 5.9 ix. Measurements of five myelocytes 

 showed average size of cell-body of 10 X 8.7 ju, with nucleus 

 7 X 5 ix. The average size of the pseudo-eosinophilic polymor- 

 phonuclears, as seen in sections, is 6.5 X 6 At. 



Six hours. After six hours, the appearance of the sections is 

 very striking from the presence of numerous myelocytes, with 

 red-staining granules. What appears to be mitotic division in 

 these cells is seen not infrequently (fig. 2, Myi). Whether this 

 may be considered a normal mitotic division has been questioned. 



The polymorphonuclears (fig. 3) are even more numerous than 

 the myelocytes, but the latter on account of their larger individ- 

 ual size form the most conspicuous elements in many fields. 

 Splenocytes are scattered here and there and have inclusions 

 similar to those in the preceding stage. There are occasional 

 extracellular masses of yellowish hemosiderin. Several mega- 

 cytes were seen, and these are apparently cells which have re- 

 mained in the spleen from fetal life, for in rodents' spleens 

 such cells are found not infrequently. One of these is shown 

 in figure 3 (M), and its size is useful for comparison with the 

 size of the splenocytes in their several stages of phagocytic 

 activity. The hemoglobinuria still persists. Within the endo- 

 thelial cells of the blood-channels very fine yellowish granules 

 could be seen. Tests for the presence of iron showed this to 

 be present within these cells and also very strikingly within the 

 splenocytes. 



