220 ESSENTIALS OF CHEMICAL PHYSIOLOGY 



same as the standard when the tube is filled up to the graduation 100, the 

 quantity of oxyhsemoglobin in the blood is normal. If it has to be diluted 

 more largely, the oxyhaemoglobin is in excess ; if to a smaller extent, it is 

 less than normal. If the blood has, for instance, to be diluted up to the 

 graduation 50, the amount of haemoglobin is only half what it ought to be 

 50 per cent, of 'the normal and so for other percentages. 



Haldane's Haemoglobinometer is more frequently used. Instead of tinted 

 gelatin, the standard of comparison is a sealed tube filled with a solution of 

 carbonic oxide haemoglobin of known strength. This keeps unchanged for 

 years. A stream of coal gas is passed through the blood to be examined. 

 This converts all the haemoglobin present into carboxyhaenioglobin ; this is 

 then diluted with water to match the standard. 



Von Fleischl's Haemometer. The apparatus (fig. 67) consists of a stand 

 bearing a white reflecting surface (S) and a platform. Under the platform is 



P 



FIG. 67. Von Pleischl's luemometer. 



a slot carrying a glass wedge stained red (K) and moved by a wheel (B). 

 On the platform is a small cylindrical vessel divided vertically into two com- 

 partments, a and a . 



Fill with a pipette the compartment ' over the wedge with distilled 

 water. Fill about a quarter of the other compartment () with water. 



Prick the finger and fill the short capillary pipette provided with the 

 instrument with blood. Dissolve this in the water in compartment a, and 

 fill it up with distilled water. Having arranged the reflector (S) to throw 

 artificial light vertically through both compartments, look down through 

 them, and move the wedge of glass by the milled head (T) until the colour 

 in the two is identical. Ptead off the scale, which is so constructed as to give 

 the percentage of haemoglobin. 



Oliver 's Haemoglobinometer. This method consists in comparing a speci- 



