-173- 



Thc iii"tli(i(ls here given are especially useriil for 

 studyiiio- the blood clinically, and can not be too warnil}- 

 reconiniendcd. 



COUNTING BLOOD CELLS. 



The instrument now generally used for this jiurpo-e is 

 the T'lioiiKi-Zclss hii'macyiometcr. This apparatus consists of 

 two parts, pipettes by means of wliich tin' blood is diluted 

 100 times, when counting red, or 10 times when white 

 blood cells are to be counted: and a glass slide, on whi<;h 

 there is a sliiall well o( known depth, the l)ottoni ol'thc well 

 being divided off into small squares. The pii)ftttj|#nsed 

 when counting the red cells, consists of a cai)illary tube, 

 near the middle of which there is an ampullar enlargement. 

 This is so graduated that the cubical contents of the capil- 

 lary tube is just one-hundredth part of the cubical con- 

 tents of the ampulla. The blood to be examined is 

 drawn into the capillary tul)e, to a line marked 1 (just be- 

 low the ampulla), the end of the pipette is then inserted 

 into the diluting fluid, and this is sucked up until the di- 

 luted blood reaches a line marked 101 (just above the am- 

 pulla). The pipette is then carefully shaken to mix 

 thoroughly the blood and the diluting fluid. 



Either of the following two solutions may be used for 

 diluting the blood : — 



Hayem's Solution. 



Bichloride of mercury, , . . 0.5 grm. 



Sodium chloride, .... 1.0 grm. 



Sodium sulphate, .... 5.0 grms. 



Distilled water .... 200.0 c. c. 



Toison's Fluid (as given by Kahlden). 



Methyl violet 5 B, . . . . 0.025 grms. 

 Neutral glycerine, .... 30.0 c. c. 

 Distilled water, .... 80.0 c. c. 



i\Iix methyl violet in glycerine and the distilled water; 



to this solution is added 



Sodium chloride (C. P.), . . 1.0 grms. 

 Sodium sulphate (C. P.), . . 8.0 grms. 

 Distilled water, . . . 80.0 c. c. 



