BLOOD. 209 



does not form a homogeneous solution the contents of the com- 

 partment should be mixed thoroughly by means of the metal handle 

 of the capillary measuring pipette. When this has been done each 

 compartment should be completely filled with distilled water and 

 the glass cover adjusted, care being taken that the contents of 

 the two compartments do not mix. Now adjust the cylinder so 

 that the compartment containing the pure distilled water is im- 

 mediately above the colored glass 

 wedge. By means of the rack 

 and pinion arrangement manipu- 

 late the colored wedge until a 

 portion of it is found which cor- 

 responds in color with the diluted 



I I I 1 M 1 1 I I I I I I I I I I I I 



blood. When this agreement in 



COLORED GLASS WEDGE OF FLEISCHL'S 



color has been secured the point H.EMOMETE*. >. ci.) 



on the scale corresponding to this 



particular color should be read and the actual percentage of haemo- 

 globin computed. For instance, if the scale reading is 90 it means 

 that the blood under examination contains 90 per cent of the normal 

 quantity of haemoglobin, i. e., 90 per cent of 14 per cent. 



2. Fleischl-Miescher Haemometer. The apparatus of Fleischl 

 has recently been modified by Miescher. If all precautions are 

 taken, the margin of error in the absolute quantity of haemoglobin 

 determined by this instrument does not exceed .0.15-0.22 per cent 

 by weight of the blood. Detailed directions for the manipulation 

 of the Fleischl-Miescher haemometer accompany the instrument. 

 In brief Miescher modified the instrument as follows: (i) The 

 scale of each instrument is supplied with a caliber table of absolute 

 haemoglobin values, expressed in milligrams : the scale of FleischFs 

 haemometer shows the percentage of haemoglobin in relation to an 

 average selected somewhat arbitrarily. Thus many errors arising 

 from the irregular coloring of the glass wedge of the older appara- 

 tus are avoided in the instrument as modified. (2) Each in- 

 strument is accompanied by a measuring pipette (melangeur) which 

 allows of a more accurate measurement of the blood than was pos- 

 sible with the capillary tubes of the older apparatus. (3) With 

 the aid of the measuring pipette mentioned above blood of varying 

 degrees of concentration may be compared. In this way the in- 

 dividual examinations are controlled and a check upon the ac- 

 curacy of the graduation in the color of the glass wedge is also 

 afforded. This wedge is much more evenly and accurately colored 





