438 



THE BLOOD 



[CH. XXVI 



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 Modification of Growers' Instrument is the one most frequently 



KK;. 371. Haanoglobinometer of Dr Gowers. 



used now, and gives very accurate results. Instead of tinted gelatin, the standard 

 of comparison is a sealed tube filled with a solution of carbonic oxide haemoglobin. 

 This keeps unchanged for years. A stream of coal gas is passed through the blood 



P 



FIG. 372. You Pleiaclil'a Hiemoglobiuo 



to be examined. This converts all the haemoglobin present into carbonic oxide 

 haemoglobin ; this is then diluted with water to match the standard. 



Von Pleischl's Hsemometer. The apparatus (fig. 372) consists of a stand 



