A QUICK, SIMPLE, AND ACCURATE METHOD OF MAKING 

 DIFFERENTIAL BLOOD COUNTS IN WET PREPA- 

 RATIONS AND ITS ADVANTAGES IN THE 

 DIAGNOSIS OF SURGICAL AND 

 TROPICAL DISEASES. 1 



By E. R. Stitt. 2 

 {From the United States Naval Hospital, Canacao, P. I.) 



In the diagnosis of acute abdominal conditions and almost to an 

 equal extent in other surgical affections, the leucocyte count has the 

 confidence of the surgeon. The same would obtain for the polymorpho- 

 nuclear percentage were it not for the errors incident to the usual method 

 of making differential counts. A smear equally distributed, a satisfactory 

 stain and good technique are necessary for results that will give true 

 findings. These three factors do not always go together, as any ex- 

 perienced laboratory worker will admit, and for the average man they 

 rarely obtain. Again, almost any variation in the leucocyte percentages 

 can be obtained in the usual easily prepared smear made with some 

 form of spreader on a slide. To make this evident it is only necessary 

 to refer to the usual method of ploughing out the polymorphonuclears 

 to the margins, a method used in preparing smears for determining the 

 opsonic index. I was told by one of our leading American laboratory 

 workers that it was necessary for him to discard several thousand smears 

 of yellow-fever blood, made for the purpose of studying leucocytie per- 

 centages in the disease, for the reason just stated. 



It has been my experience that the only method of making films 

 which gives fairly accurate findings is that of Ehrlich — the sliding apart 

 of two cover glasses between which the drop of blood has distributed itself 

 in a thin layer. Even with this procedure we meet sources of error 

 such as the difficulty of distinguishing poljTnorphonuclears from tran- 

 sitionals in those portions of the smear which fail to show a single 

 layer of red cells and in particular by reason of the large number of 

 disrupted cells which are peculiarly common to pathologic blood and 



1 Read at the first biennial meeting of the Far Eastern Association of Tropical 

 Medicine, held at Manila March 12, 1910. 

 3 Surgeon, United States Navy. 



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