METHOD OF COUNTING BLOOD-CORPUSCLES. 



33 



merit, whose tip is dipped into the blood, which by suction through a rubber tube 

 is drawn into the pipet either to the mark \ or to the mark i. The tip carefully 

 dried is then immersed in 3 per cent, sodium-chlorid solution, which is sucked up 

 until it reaches the mark 101. By shaking the mixer a spherule (a) in the bulbous 

 enlargement of the apparatus is moved about so as to effect a homogeneous mix- 

 ture. If the blood be sucked up to the mark \ the mixture will be as i to 200, 

 and if up to the mark i as i to 100. 



For the enumeration of the cells a small amount of the blood-mixture is intro- 

 duced into the Abbe-Zeiss counting-chamber (Fig. 2) , the first few drops being 

 thrown away. Upon a slide is cemented a glass cell, o.i mm. deep, upon whose 

 floor are etched a series of squares and which is surrounded by a groove or depres- 

 sion and is provided with a cover-glass to be placed over it. The space overlying 

 each square has a capacity of ?7T Vo cu. mm. The number of cells in each square 

 is estimated and this multiplied by 4000 gives the number of corpuscles in each 



FIG. 2. Apparatus of Abbe and Zeiss for Counting the Cor- 

 puscles: A, in section; C, surface view without cover- 

 glass; B, microscopic appearance with the blood-cor- 

 puscles. 



FIG. 3. The Melangtur, 

 pipet or mixer. 



cu. mm. The result thus obtained must be multiplied by 100 or 200, according 

 as the blood has been diluted 100 or 200 times. To ensure greater accuracy the 

 contents of a large number of squares should be counted and the average take 

 Vierordt, Malassez, Gowers, and others have devised similar forms of apparatu 

 for the same purpose. 



To count the white blood-corpuscles alone in the chamber the blood i 

 with 10 parts of a per cent, solution of acetic acid, which dissolves out the red 

 corpuscles. It is advisable to stain the leukocytes in the blood-mixer, and 

 can be done with some such solution as the following: 50 cu. cm of a I per c 

 of solution of sodium chlorid with 5 drops of a 5 per cent, alcoholic s 

 gentian-violet or hexamethyl-violet. 

 3 



