THE RED BLOOD CORPUSCLES 177 



pipet until either point 0.5 or 1 has been reached. The end of the 

 pipet is then dried with filter paper and immediately dipped into 

 an isotonic solution 1 which is intended to dilute the blood previously 

 drawn in. The tube is then filled to point 101 above its bulbular 

 enlargement. Upon its withdrawal from the fluid it is again dried 

 with filter paper and gently shaken until the blood and the solution 

 have become thoroughly mixed. The marks upon the tube signify that 

 if the blood is drawn in as far as point 1 and the diluting fluid as far as 

 point 101, the original sample of blood is diluted 100 times, whereas, 

 if the marks 0.5 and 101 are used, a dilution of 200 times is the result. 



Having thoroughly mixed the contents of the pipet, a drop or two 

 are permitted to escape from the tube without being used. The next 

 droplet, however, is collected upon the stage of the counting chamber 

 (C) and in such a manner that it does not overflow into the space 

 next to it. The entire compartment is then closed by placing a cover- 

 glass over it. The surface of the stage is exactly 0.1 mm. below the 

 lower surface of the cover-glass. A series of 20 squares are engraved 

 upon the former, the sides of which measure ^Q mm. in length, and 

 hence, each possesses an area of 1^00 S< 1' mm - an d a capacity of 

 J^oo X 0.1 = Mooo cu. -mm. Having counted the number of cor- 

 puscles in many of these small squares, a fair average value is 

 obtained from these figures. The value so obtained is then multi- 

 plied by the degree of dilution and by 4000. 



It is only natural to suppose that the size and number of the red 

 corpuscles must preserve an indirect relationship to one another. 

 That this is true, is borne out by the following table 2 which should be 

 compared with the one containing the data pertaining to the size of 

 the different red cells. 



1 Various preserving solutions have been recommended, for example : 



(a) Hayem's fluid: 



Hydrarg. bichlor 0.5 gram. 



Sodii sulphat 5.0 grams. 



Sodii chlorid 2.0 grams. 



Aq. distill 200.0 c.c. 



(6) Gower's fluid: 



Sodii. sulphat. gm 104 . 



Acid acetic 3i 



Aq. destill g. s. ad. giv 



(c) Toisson's fluid: 



Aq. destill 160.0 c.c. 



Glycerin 30. c.c. 



Sodii sulphat 8.0 grams. 



Sodii chlorid 1.0 gram. 



Methyl violet . 025 gram. 



2 Storch, Unters. iiber den Blutkorperchengehalt des Blutes, etc. Disserta- 

 tion, Bern, 1901; Musser and Krumbhaar, Folia hematologica, xviii, 1914, 576, 

 and Wells and Button, Am. Jour, of Physiol., xxxix, 1915, 31. 



12 



