EXAMPLES 95 



of 5 cc. of "coefficient jelly" add 5 units (0.5 cc.) of 

 stain, 3 units of alkali (0.3 cc. of a 5-per-cent sodium 

 bicarbonate solution) , and 4.2 cc. of water to make 

 it up to the 10 cc. of jelly. The film is prepared as 

 before, and it is incubated at 37 C. for 10 minutes. 

 On examination, it will be seen that the nuclei of the 

 neutrophile cells are just turning scarlet. Hence this 

 jelly at 37 C. in 10 minutes has the right Index of 

 Diffusion for the coefficient of diffusion of neutrophile 

 leucocytes. The equation may be thus set down: 



Neutrophile leucocytes 



cf = (5s 



The lymphocytes have a cf of 14 (2 units higher 

 than that of the neutrophile cells). We may cause 

 their nuclei 1 to stain in 10 minutes at 37 C. by using 

 a jelly similar to the last one, but by either increasing 

 the amount of alkali by 2 units, or by increasing the 

 concentration of the stain by 2 units, or by increasing 

 the alkali by 1 unit and the stain by 1 unit; or by 

 increasing the time by 2 units. Let us try a jelly 

 which contains 2 more units of stain, for now the 

 chromatin of the cells will stain deeply and show up 

 well. The jelly is made thus: To a tube of 5 cc. 

 of "coefficient jelly" add 7 units (0.7 cc. of stain), 3 

 units of alkali, and, since we now have more stain, 

 only 4 cc. of water is needed to make the contents 

 of the tube up to 10 cc. The whole mixture is boiled 

 and a drop of it spread on a slide in the usual manner. 

 After the blood has been mounted on it the slide is 



1 See Chapter XII. 



