14 CONCERNING THE RULES AND APPLIANCES 



The blood half of the comparing vessel, after the graduating 

 tube has been rinsed, should not be much more than half full, 

 never more than three-quarters full of the liquid, first, in order to 

 make a thorough mixing of the contents possible, and second, in 

 order to permit of a last stratum of water above the blood solution. 

 This portion of water renders the overflowing of the partition wall 

 an immaterial instead of a ruinous occurrence. The liquid in the 

 blood half may now be moved with perfect freedom, a thin wire 

 being used to stir it. In the absence of a wire, the handle of a 

 blood pipette may be used ; but in this case the loop which forms 

 the end is an inconvenience, since it prevents the wire from 

 reaching the corners at the bottom of the vessel. And exactly 

 these corners, as well as the angles formed by the bottom and the 

 walls, as also those formed by the partition wall and the mantle of 

 the half cylinder, are the favourite sites of very concentrated parts 

 of the solution. The particles of blood may be so slightly 

 dissolved that no complete dissolution of the hemoglobin in the 

 water, and even no perfect destruction of the stromata of the red 

 blood cells has taken place in order to secure the haemoglobin in 

 the solution, in consequence of which the liquid appears turbid. 

 The angles and corners are to be noticed especially, and should 

 be continually observed until neither inequality of colour in the 

 liquid in the blood half of the vessel nor the slightest turbidness 

 can be detected. This of course takes place while the light shines 

 through it, since the vessel has already been set into the instru- 

 ment (Haemometer). 



When these things have all been arranged, it is time to proceed 

 to the filling of the blood half of the comparing vessel. It is not 

 worth while to rinse back into the vessel the very small portion of 

 the blood solution which clings yet to the end of the wire used to 

 stir it. Pure water from the pipette is then dropped into the 

 blood solution, care being taken that the liquid in the vessel is 

 disturbed as little as possible. With a little practice it may be 

 risked to allow the last quantity of water to flow in, instead of 

 being dropped, while the end of the pipette is dipped slightly 

 beneath the surface of the liquid. The blood half, and also the 

 wedge half, should be filled to the level of the rim, so that no 

 meniscus may occur, but the liquid in both halves may have a 



