PRACTICAL EXERCISES 



drop by drop with the pipette stopper of the bottle E, which is used 

 for holding the water, the tube being inverted after each, addition, 

 till the tint in B is the same as that in A. In comparing the tubes, 

 they should be held against the light from the sky or from an opal 

 glass lamp-shade. It is necessary to transpose the tubes repeatedly. 

 The level at which the tints are equal is read off on B half a minute 

 after the addition of the last drop of water. Water is now again added 

 by drops till the tint in B is just roticeably weaker than in A, and the 

 mean of the two readings is taken. The result is the percentage actually 

 present of the average proportion of haemoglobin in the blood of healthy 

 adult males. Healthy women give an average of only 89 per cent., 

 and healthy children an average of only 87 per cent., of the proportion 

 in men. The liquid in A is a i per cent, solution of blood containing 

 the average percentage of haemoglobin found in the blood of healthy 



Fig. 22. Haldane's Modification of Gowers' Haemoglobinometer. 



adult males, and having an oxygen capacity of 18 5 per cent. i.e., 

 100 c.c. of the blood with which the standard was made would take 

 up in combination from air 18-5 c.c. of oxygen. The solution in A has 

 been saturated with carbonic oxide. 



This method is probably more accurate than any other used in clinical 

 work, the error, in the hands of an experienced observer, not exceeding 

 i per cent. 



(b) By Fleischl's Hcemometer (Fig. 23). Fill with distilled water that 

 compartment a' of the small cylinder (above the stage) which is over 

 the tinted wedge. Put a little distilled water into the other compart- 

 ment a. Now prick the finger and fill one of the small capillary tubes 

 with blood. See that none of the blood is smeared on the outside of 

 the tube. Then wash all the blood into the water in compartment a, 

 and fill it to the brim with distilled water. By means of the milled 



