Studies on the Blood of the Albino Rat. 133 



plates themselves, however, differ greatly in size, measuring from 

 two to five micra in long diameter. In the diluting fluid they 

 usually appear slightly oval and cup-shaped. They are granular. 

 Varied forms, however, may be seen in the dry and stained pre- 

 parations. The red blood cells, even in healthy rats, always 

 show considerable granular degeneration and polychromatophilia. 

 The total number of leucocytes is high as compared with the human 

 count and, as shown in the table, has a wide variation in apparently 

 normal animals. The reaction to an inflammatory process com- 

 monly results in a high leucocytosis. Several counts of over 

 45,000 per c.c. were made. Two were in cases of large subcu- 

 taneous abscesses, two in cases of ulcerating sarcoma. 



The differential count of leucocytes in normal animals shows a 

 fairly constant percentage of polymorphonuclear cells. The total 

 number of mononuclear cells is also fairly definite, but there is 

 great variation in the proportion of large and small cells in different 

 animals. While the small mononuclear cells usually greatly 

 outnumber the large, two apparently normal rats showed more 

 large than small cells. 



In five albino rats inoculated with sarcoma the blood was 

 observed. The results agree in general with those of Pappenheim 

 and of Hirschfeld. No marked change in the blood picture is 

 noticeable during the growth of the tumor except an increase in 

 the amount of polychromatophilia of the red cells and a slight 

 increase of small mononuclear leucocytes at the expense of the 

 large mononuclear and transitional cells. When the tumor was 

 of an ulcerating character, however, leucocytosis was marked : 

 45,000 in one, 50,000 in another rat. Blood plates remained 

 stationary. 



Benzol leucopemia was readily produced in two rats, the 

 leucocyte count falling from 15,000 to 1,200 in one, and from 

 25,000 to 2,200 in the other; while the plates showed a correspond- 

 ing drop from 850,000 to 500,000, and from 1,000,000 to 500,000 

 respectively inside of ten days. The fall in leucocytes was pro- 

 portionately greater in the large mononuclear and transitional 

 cells than in the polymorphonuclear and small mononuclear 

 cells. 



