10 QUATERCENTENARY STUDIES IN PATHOLOGY 



obtained averages of 88449, I5>998"6, and 14,6777 respectively. 

 Brinckerhoff and Tyzzer (34) found a variation of 4000 to 12,000. 



In our own experiments we obtained from a series of 25 normal 

 healthy rabbits an average leucocyte count of 10,533 with a variation of 

 4500 to 17,200. 



Far more important than these large variations in different rabbits, is 

 the consideration of those minor variations which may occur in the 

 counts of individual animals independently of experiment, and which, if 

 neglected during experiments on leucocytosis, may give rise to fallacies. 



It would appear sufficient to ascertain the leucocyte count of the 

 animal on three or four days prior to the experiment, such counts being 

 made at the same hour every day, and under similar conditions as to 

 feeding or fasting. 



Brinckerhoff and Tyzzer {loc, cit.) recommend more elaborate 

 precautions. Before experiments on leucocytosis, they make careful 

 observations of the influence of fasting or feeding on the leucocyte count, 

 and finally select those rabbits only whose leucocytes decrease during a 

 period of fasting. For a short experiment, the animal should be allowed 

 to fast for 12 to 20 hours, and if during this time the leucocyte count 

 does not rise, the experiment may be carried out with the assurance that 

 for a time the variations in the leucocyte count will be unworthy of 

 consideration. Other influences to be reckoned with, such as loss of 

 body heat, shock and pregnancy, are obvious. In our experiments it did 

 not appear to us either advisable or humane to keep the animals without 

 food even during short experiments lasting six to eight hours. After the 

 inoculations the animals invariably showed a loss of appetite throughout 

 the course of the experiment, so that any small errors due to digestion- 

 leucocytosis might be neglected. Further, as we were able to demonstrate 

 in many control animals, the slight rises, due to feeding, came well within 

 the experimental error with our available counting methods, 



Pohl (35), who investigated this question of digestion-leucocytosis, 

 came to the conclusion that the phenomenon was marked only in those 

 animals such as the dog, which received meals once or twice a day, and 

 was quite inconsiderable in animals like the rabbit, whose stomachs were 

 continually full. 



(330) 



