Abstract
During the course of a standardization of the blood of fowls, undertaken as a part of a series of studies upon acid fast infections in various species of animals, it was found that no direct method existed for making total white blood counts upon avian blood. The methods commonly employed for mammalian blood, which embody the principle of destruction of the red cells in order that the white cells may thereby be counted without confusion, are not satisfactory for avian blood. This is because the circulating red blood cells in the bird are nucleated and, while acetic acid solutions hemolyze the red cells, they will not destroy their nuclei; the latter are thus liberated and are almost indistinguishable from small lymphocytes.
Because of this difficulty, various indirect methods based upon the ratio of red blood cells to white cells in the same smear were devised for making estimations of the total white cell counts of the bird. The reports in the literature for the blood of normal fowls when such methods were employed are quite divergent. Among the most careful studies that have been reported are those of Schmeisser 1 and of Warthin. 2 The former determined the ratio of red blood cells to white blood cells from smears stained with Wilson's stain. He found the ratio to vary between 1 to 40 and 1 to 150 with an average of 1 to 50. Using these ratios he calculated the total white blood counts and found they varied between 20,000 and 80,000 cells per cmm. Warthin, with similar technique, found the ratios between red cells and white cells to vary between 1 to 102 and 1 to 225, and the total white counts to vary between 12,000 and 29,000 cells per cmm.
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