26 



THE H^EMOGLOBINOMETER. 



[ (d. ) The HsBmOglobinometer of Gowers is used for the clinical estimation of 

 haemoglobin.] 



" The tint of the dilution of a given volume of blood with distilled water is 

 taken as the index of the amount of haemoglobin. The distilled water rapidly 

 dissolves out all the haemoglobin, as is shown by the fact that the tint of the 

 dilution undergoes no change on standing. The colour of a dilution of average 

 normal blood one hundred times is taken as the standard. The quantity of 

 haemoglobin is indicated by the amount of distilled water needed to obtain the 

 tint with the same volume of blood under examination as was taken of the 

 standard. On account of the instability of a standard dilution of blood, tinted 

 glycerine -jelly is employed instead. This is perfectly stable, and by means of 

 carmine and picrooarmine the exact tint of diluted blood can be obtained. 



The apparatus consists of two glass tubes of exactly the same size. One contains 

 (D) a standard of the tint of a dilution of 20 cubic m.m. of blood, in 2 cubic centi- 

 metres of water (1 in 100). 



The second tube (C) is graduated, 100 degrees = two centimetres (100 times 

 twenty cubic millimetres). 



The twenty cubic millimetres of blood are measured by a capillary pipette (B) 

 (similar to, but larger than that used for the haemacytometer). This quantity of 

 the blood to be tested is ejected into the bottom of the tube, a few drops of distilled 

 water being first placed in the latter. The mixture is rapidly agitated to prevent 

 the coagulation of the blood. The distilled water is then added drop by drop 

 (from the pipette stopper of a bottle [A] supplied for that purpose) until the tint of 

 the dilution is the same as that of the standard, and the amount of water which has 

 been added (i.e., the degree of dilution) indicates the amount of haemoglobin. 



Since average normal blood yields the tint of the standard at 100 degrees of 

 dilution, the number of degrees of dilution necessary to obtain the same tint with 



a given specimen of blood 

 is the percentage propor- 

 tion of the haemoglobin 

 contained in it, compared 

 to the normal. 



For instance, the 20 

 cubic millimetres of 

 blood from a patient 

 with anaemia gave the 

 standard tint at 30 

 degrees of dilution. 

 Hence it contained only 

 30 per cent, of the normal 

 quantity of haemoglobin. 

 By ascertaining with the 

 haemacytometer the cor- 

 puscular richness of the 

 blood, we are able to 

 compare the two. A 

 fraction, of which the 

 numerator is the per- 



Fig. 9. 



A, pipette bottle for distilled water; B, capillary pipette; centage of haemoglobin, 

 C, graduated tube ; D, tube with standard dilution ; and the denominator 

 F, lancet for pricking the finger. the percentage of cor- 



puscles, gives at once 



the average value per corpuscle. Thus the blood mentioned above containing 30 

 per cent, of haemoglobin, contained 60 per cent, of corpuscles ; hence the average 



