Considerable study has been carried out on the normal variation in the number of leukocytes in the capillary blood. It is not our intention in this paper to review the subject, and the reader may be referred to a previous article by one of us 1 and to recent articles by Sabin and her co-workers 2 and by Shaw.3 Briefly summarized, the observations made by different investigators are as follows:
In children and adults, digestive leukocytosis is inconstant.
A rise in the total leukocyte count occurs in the afternoon and also in the early morning, regardless of the effect of food.
Animals such as dogs, cats and rabbits develop a leukocytosis after food rich in protein.
Protein food seems to be more constantly productive of leukocytosis than carbohydrate or fat.
Several factors influence the number of leukocytes as ordinarily counted in the capillary blood. Among