THE BLOOD. 195 



to be examined, water being added to the latter until the exact shade 

 of the standard solution is obtained. 



Von Fleischl's Haemometer. This instrument consists of A, a 

 cylindrical cell for holding the prepared blood; D 9 a graduated 

 wedge-shaped piece of colored glass with which to compare the solu- 

 tion of blood; 7f, a stand with a rack and pinion; and a capillary 

 tube for measuring the quantity of blood required. 



1. The cell (A) is a cylindrical metallic chamber divided by a 



Fig. 68. Von Fleischl Haemometer. (LAHOUSSE.) 



A, Mixing vessel with two compartments: B, for diluted blood; C, for 

 pure water, reposes over the colored prism of glass, D. E, Scale to read off 

 amount of haemoglobin. M, A mirror to reflect light. E, Milled wheel that 

 moves D. 



fixed partition into two equal compartments, open at the top, but 

 closed at the bottom by a base of glass. One of these compartments 

 is to be filled with distilled water, the other with the proper quan- 

 tity of blood dissolved in distilled water. 



2. The colored glass wedge (D) is fitted to a metal frame, so 

 that it can be adjusted in the stand and moved from side to side 

 by the rack and pinion. When in position the glass wedge moves 

 directly beneath that part of the cell which contains the distilled 

 water, thus enabling one to compare the color of the glass with that 

 of the dissolved blood which fills the adjoining compartment of the 



