LVIII. Counting red and white corpuscles. 



1. Appliances. Microscope with one- seventh objective; 

 needle and holder; Thoma-Zeiss counter with small 

 lumened pipette. 



2. Preparation. Prepare the following solution for staining: 



TOISSON'S SOLUTION. 



Methyl violet, 5 b ' 025 gm. 



Sod.chlor 1.000 gm. 



Sod. sulph 8.000 gm. 



Neutral glycerin 30.000 cm. 



Aqua dist 160.000cm. 



j. Operation. Obtain blood as described above and dilute 

 1 to 200 with Toissorfs solution. Place the counting slide 

 under the microscope and find the upper left-hand square; 

 count the red corpuscles in each square from left to 

 right; then retrace the same field and count the white 

 corpuscles. Repeat this procedure with the next row of 

 squares, continuing the same way until all the squares 

 are counted. Write the number of red corpuscles on 

 one side of a line, the white on the other. Clean the 

 counter; agitate the pipette, blow out a drop, place the 

 solution on the counter and count as before. If there is 

 much variation between the number of first and second 

 field, count a third field and take the average of the 

 two fields nearest alike. Divide the total number of 

 corpuscles by total number of squares counted; multiply 

 by 200 (amount of dilution) and then by 400, which will 

 give number of corpuscles per cubic millimeter. The 

 use of this staining fluid enables the student to count 



