THE BLOOD. 



247 



c.mm. With a graduated pipette 20 cubic millimeters of blood are 

 accurately measured and blown into the bottom of the tube B, in 

 which a few drops of distilled water have been placed so as to prevent 

 coagulation. Water is then added drop by drop until the color of 

 the diluted blood is exactly that of the standard. The division of 

 the scale reached by the dilution will represent the relative per- 

 centage of hemoglobin. If this tint is not obtained until the dilu- 

 tion reaches 100 divisions, the quantity of hemoglobin is normal. 

 If more water must be added, it is in excess; if less, it is diminished. 

 If, for example, the 20 cubic millimeters of blood from an anemic 

 patient gave the standard tint at 60 divisions, the blood contained 

 but 60 per cent, of the normal amount of hemoglobin. 



FIG. 102. GOWERS' HEMOGLOBINOMETER. A. Pipette bottle for distilled water. 

 B. Capillary pipette. C. Graduated tube. D. Tube with standard dilution. 

 F. Lancet for pricking the finger. (Landois and Stirling.) 



Von FleischPs hemometer consists of a metallic cell divided into 

 two compartments, a and a', by a vertical partition (Fig. 103). In 

 the former a definite quantity of blood is placed and diluted with a 

 known quantity of water. Beneath the compartment a' is placed 

 a glass wedge stained with the golden purple of Cassius or simi- 

 lar pigment, the color of which passes from a deep red at one end to 

 clear glass at the other (Fig. 104). To the side of this wedge is 

 placed a scale ranging from o to 120. By means of the screw, 

 R T, the glass wedge is moved until the color of the glass and 

 diluted blood is identical. The illumination of the blood and glass 

 wedge is accompanied by lamplight reflected from the white reflect- 

 ing surface beneath. The depth of color of the glass opposite 100 on 



