On the Fluctuations in tlie Number of wliite Blood Corpuscles etc. 59 



endeavour must be directed towards obtaining a constant blood- 

 mixture. 



I may now briefly describe my experiments to ascertain the 

 accuracy of the method of counting. 



My preparations were also made according to the acetic acid 

 method; in counting a Breuer's cell was used with Leitz Obj. 3, 

 Oc. I. On multiplying the number obtained by 2009 we get the 

 number of leucocytes in a cubic mm4 



It will be surprising to most that Bruhn-Fåhræus, who avoids 

 a number of sources of error, has obtained a much greater error 

 than Kjer-Petersen, though the latter determines the total error in 

 variable blood. The difference is so considerable, that it cannot be 

 considered as arising from personal peculiarities in the two investi- 

 gators. The method is not so extremely complicated and the com- 

 paratively inexperienced assistant of Kjer-Petersen has thus obtained 

 just as good a result as himself, in counting the corpuscles in the 

 "constant" man. 



To come to a clearer understanding of this condition, as also 

 to ascertain which of the manipulations necessary in the counting 

 give the greatest uncertainty in the result, I began by counting 2 

 drops from the same pipette (I had only two measuring cells at 

 my disposal). I obtained considerably different results, which I 

 ascribed to my relative lack of experience in counting; but it grad- 

 ually became more and more evident, that whilst I obtained uni- 

 form results on counting the same number of drop from two differ- 

 ent pipettes, two drops from the same pipette gave different results 

 in spite of previous theorisings. 



The following results are characteristic. 



О 



1 A circumstance which caused great trouble in all investigations of the blood, 

 especially in winter, луаз the extraordinary rapidity with which the blood coagu- 

 lated. It was almost impossible sometimes to get a pipette filled up to the 

 usual mark without the blood rising up into the holder in one clump, л\'Ь1сЬ 

 could not be shaken down. (With regard to this condition, see for the rest 

 Bojanus: Exper. Beiträge z. Physiologie u. Pathologi d. Blut d. Säugethiere 

 Dorpat 1881. S. 18). 



