140 THE BLOOD 



Fleischl, of Vienna. In this instrument the amount of hemoglobin in a 

 solution of blood is estimated by comparing a stratum of diluted blood with 

 a standard solid substance of uniform tint similar spectroscopically to diluted 

 blood. The Fleischl instrument has been somewhat modified and made 

 more accurate by Miescher. The Fleischl-Miescher apparatus consists of a 

 stand with a metal plate having a circular opening and a plaster mirror below, 

 S, figure 122, which casts light through the opening. Beneath the plate is a 

 metal framework containing a colored glass wedge, and along the side of 

 the same is a scale graduated so as to indicate the percentage of hemoglobin 

 corresponding to the shades of the different parts of the wedge. This frame- 

 work can be moved by the wheel T which fits into a rack on its lower surface. 

 The scale can be read through a small opening M in the plate. Into the 

 large circular opening of the plate fits a cylindrical metal cell G with a glass 

 bottom and divided by a metal partition into two equal parts. One of these 

 halves lies over the wedge and is filled with distilled water. The other con- 

 tains the solution of blood in which the hemoglobin is to be estimated. The 

 apparatus is usually supplied with three cells. Of these, the first two are 

 used in estimating the hemoglobin according to Miescher' s modification 

 of Fleischl' s original method. This is the method now generally used. 

 These cells are furnished with a glass cover having a groove \vhich fits 

 upon the partition of the cell. Over this cover is placed a diaphragm 

 w T ith a longitudinal slit, which only permits of the central part of each side 

 of the cell being seen. The third cell is for use when the original Fleischl 

 method is employed. 



The patient's ear or finger is pricked, and the blood from the wound 

 sucked up into the graduated pipet until it reaches the mark J, f , or -f, a 

 i per cent, solution of sodium carbonate is then sucked in until the upper 

 mark is reached. The pipet is then well shaken in order to mix the blood 

 thoroughly. One-half of each of the two cells, which are, respectively, 12 

 and 15 millimeters high, is then filled with the mixture, the other half 

 being filled with water. An important point is that the liquids should com- 

 pletely fill the cells. The cover-glasses and diaphragms are then applied 

 and the cells are ready for examination. This must be done by artificial 

 light. Moreover, in order to have accurate results, light of the same inten- 

 sity should be always used. One of the cells is placed on the plate and the 

 wheel T turned until the colors of the two halves exactly correspond. When 

 this point is reached, the result is read off on the scale through the opening 

 M. This should be repeated several times with each of the cells, and the 

 average of the readings taken. The result obtained with the 1 2-millimeter 

 cell should be multiplied by f to bring it up to that of the larger. For example, 

 suppose the result of several readings to be: 



With the large cell (15 mm.) 54 . oo 



With the small cell (12 mm.) 42 .00 



