v BLOOD ANALYSIS 3OI 



responding to this particular color should be read and the actual percentage of 

 hemoglobin 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 hemo- 

 globin, i.e., 90 per cent of 14 per cent. 



2. Fleischl-Miescher Hemometer. The apparatus of Fleischl 

 has been modified by Miescher. If all precautions are taken, the 

 margin of error in the absolute quantity of hemoglobin 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 hemometer accompany the in- 

 strument. In brief Miescher modified the instru- 

 ment as follows: (i) The scale of each instrument 

 is supplied with a caliber table of absolute hemo- 

 globin values, expressed in milligrams: the scale of 



FIG. 90. PIPETTE 

 Fleischl s hemometer shows the percentage of hemo- OF FLEISCHL'S 



globin in relation to an average selected somewhat HEMOMETER - 

 arbitrarily. Thus many errors arising from the irregular coloring of the 

 glass wedge of the older apparatus are avoided in the instrument as 

 modified. (2) Each instrument is accompanied by a measuring pip- 

 ette (melangeur) which allows of a more accurate measurement of the 

 blood than was possible with the capillary tubes of the older appara- 

 tus. (3) With the aid of the measuring pipette mentioned above 

 blood of varying degrees of concentration may be compared. In this 

 way the individual examinations are controlled and a check upon the 



accuracy of the graduation in the 

 color of the glass wedge is also 

 afforded. This wedge is much 

 more evenly and accurately colored 

 than in the unmodified apparatus 



of Fleischl. (4) Before reading 

 FIG. 91. COLORED GLASS WEDGE OF . 



FLEISCHL'S HEMOMETER. (Da Costa.} the percentage as indicated by the 



scale, the chamber is covered with 



a glass and a diaphragm which sharply define the field on all sides 

 without the formation of a meniscus. 



The measuring pipette is constructed essentially the same as the 

 pipettes which accompany the Thoma-Zeiss apparatus (see page 305). 

 The capillary portion, however, is graduated, i, 2/3 and 1/2 which 

 enables the observer to dilute the blood sample in the proportion of 

 i :2oo, i :3oo or i 1400 as he may desire. If there is difficulty in 

 drawing in the blood exactly to one of the graduations just mentioned 

 the amount of blood above or below the volume indicated by the gradu- 

 ation may be determined by means of certain delicate cross-lines which 



