BLOOD ANALYSIS 



305 



rington's solutions. 1 When either of these solutions is used as the dilut- 

 ing fluid it is possible to make a very satisfactory count of both the 

 erythrocytes and leucocytes from the same prepara- 

 tion, since the leucocytes are stained by the methyl r 

 violet or methylene-blue. 



In counting the erythrocytes by means of the hemo- 

 cytometer, proceed as follows : Thoroughly cleanse the tip 

 of the finger or lobe of the ear of the subject by the use of 

 soap and water, alcohol and ether applied in the sequence 

 just given. Puncture the skin by means of a needle or 

 scalpel and allow the blood drop to form without pressure. 

 Place the tip of the pipette in contact with the blood drop, 

 being careful to avoid touching the skin, and draw blood into 

 the pipette up to the point marked 0.5 or i according to 

 the desired dilution. Rapidly wipe the tip of the pipette 

 and immediately fill it to the point marked 101 with Toison's 

 or Sherrington's solution. Now thoroughly mix the blood 

 and diluting fluid within the mixing chamber by tapping 

 the pipette gently against the finger, or by shaking it while 

 held securely with the thumb at one end and the middle 

 finger at the other. After the two fluids have been 

 thoroughly mixed the diluting fluid contained in the capil- 

 lary-tube below the bulb should be discarded in order to in- 

 sure the collection of a drop of the thoroughly mixed blood 

 and diluting solution for examination. Transfer a drop from 

 the pipette to the ruled floor of the counting chamber and, 

 after placing the cover-glass firmly in position, 2 allow an in- 

 terval of a few minutes to elapse for the corpuscles to settle 

 before making the count. Now place the slide under the 

 microscope and count the number of erythrocytes in a num- 

 ber of squares, counting the corpuscles which are in con- 

 tact with the upper and the right-hand boundaries of the 



FIG. 96. THOMA- 

 ZEISS CAPILLARY 

 PIPETTES. 

 A, Erythrocytometer; 



B, Leucocytometer. 



1 Toison's solution has the following 

 formula: 



Methyl-violet o . 025 gram. 



Sodium chloride i gram. 



Sherrington's solution has the following 

 formula: 



Methylene-blue o. i gram. 



Sodium chloride 1.2 gram. 



Sodium sulphate 8 grams. Neutral potassium oxalate 1.2 gram. 



Glycerol 30 grams. Distilled water 300.0 grams. 



Distilled water 160 grams. 



- If the cover-glass is in accurate apposition to the counting cell Newton's rings may be 

 plainly observed. Eustis (Jour. Am. Med. Ass'n, 61, 1984, 1913) suggests the following 

 technic: "After the usual shaking of the pipette, and expulsion of a few drops of the 

 suspension, a good sized drop is placed on the counting chamber, no particular atten- 

 tion being paid to its size. The cover-glass, which has been previously cleaned, is 

 then rapidly grasped between the thumb and index-finger of the right hand, while the 

 slide is steadied on the table with the left hand. While firm pressure is exerted on the 

 cover-glass it is rapidly slid across the counting chamber, through the drop of suspen- 

 sion on it. The cover-glass will cut through the drop at exactly o.i mm. The excess 

 from the drop will rise on top of the cover-glass and jump across the moat. Newton's 

 rings will be obtained in each instance. The drop on top of the edge of the cover- 

 glass is wiped or soaked up with the point of a towel or blotting-paper and the preparation 

 is completed." 



