SOME OBSERVATIONS REGARDING EOSINOPHIEES 
Lewis H. Wright 
Nevada Agricultural Experiment Station 1 
During the past few years our knowledge of the relationship of a para¬ 
sitic infestation and an eosinophilia has been undergoing considerable 
revision. Not so very long ago the presence of an unusually large num¬ 
ber of eosinophiles was considered almost diagnostic of a severe infesta¬ 
tion with some form of external or internal parasites. Also an absence 
of an eosinophilia presented very strong evidence that the animal was 
almost if not entirely free from parasitism. 
The observations reported here are based on a study of 40 cases. 
From 1 to more than 20 blood examinations have been made on the 
individual cases, some of which extended over a period of about 18 
months. In all the cases the animals were carefully autopsied and a 
close search for internal parasites was made. None of the animals 
were harboring external parasites. 
The usual precautions for drawing the blood and making the examina¬ 
tions were observed. The place chosen for procuring the blood was the 
under surface of the tail. In case this failed, the skin was shaved at the 
shoulder and the incision made there. As a rule, Tallquist’s hemoglobin 
scale was used, although Gower’s method was used in some instances. 
Both red and white cells were counted in the same preparation, a double- 
ruled Neubauer counting chamber being used in most cases. For the 
differential count Giemsa’s stain was ordinarily used, but Wright’s 
and Jenner’s were sometimes used. Five hundred cells were usually 
counted, although sometimes 1,000 were counted. 
The writer is indebted to Dr. Edward Records for checking some of 
the differential counts. While the two counts did not absolutely check, 
they were very close. It is not to be expected that even two counts by 
the same person on the same slide would be identical. 
1 Resigned June 1, 1920. 
Vol. XXI, No. 9 
Aug. 1, 1921 
Key No. Nev.-i 
Journal of Agricultural Research, 
Washington, D. C. 
yy 
(677) 
