50 LABORATORY METHODS OF 



3. Constrict the part above the puncture and obtain 

 another drop. 



4. Place this drop on the slide and cover, or touch 

 the edge of two clean cover-glasses to the drop, so that 

 a very thin spread of blood can be secured between 

 them; place on the slide and examine. 



5. Note the shape of the red cells; the manner of 

 grouping on the slide ; search for nuclei ; look for stain 

 in the cells ; note the central part of the cell, and meas- 

 ure the cell with the micrometer. 



6. In the same preparation examine the white cor- 

 puscles which are found adhering to the slide. 



Exercise No. 31. Use the Haemacytometer, count the 

 cells of both varieties, in a c.m. 



1. Take 995 c.m. of sodium sulphate solution; spe- 

 cific gravity, 1028; temperature, 15 C. 



2. Take 5 c.m. of the blood. 



3. Mix in the mixing jar with the spud. 



4. Take the instrument and fill the cell with the 

 mixed blood and solution. 



5. Place the instrument under the microscope and 

 let the whole stand a few minutes ; then count the num- 

 ber of cells in ten squares; strike the average; then 

 multiply the average by 10,000, since the blood has 



