140 SPECIAL PHYSIOLOGY 



waving it back and forth in the solutions for a moment or two. 

 Then carefully dry the tube by blowing air through it, holding the 

 tube about two inches from the mouth so as to avoid the moisture 

 of the exhaled air. Fill each side of the metallic cup about three- 

 fourths full of distilled water. Prepare the needle and the ear or 

 finger as in other tests. 



Technique. Obtain the blood in the usual manner. Hold the lobe 

 of the ear with the thumb and finger. Use the second drop. Hold 

 the capillary tube horizontally and carefully touch the drop of blood 

 with the end of the tube only. If the tube is clean it will fill rapidly 



FIG. 69 



Fleischl's hsemometer. 



by capillary attraction. If there is any blood on the outside of the 

 tube or air-bubbles inside, it must be cleaned, dried, and refilled 

 properly. If the capillary is overfull, remove the excess by touching 

 the tip to a cloth or filter paper. Then quickly put the capillary 

 tube into the water in one compartment of the metallic cell and wave 

 it back and forth or up and down, and the blood, if fresh enough, will 

 readily mix with the water; then allow a few drops of water from the 

 medicine dropper to flow through the capillary into the same com- 

 partment to wash the blood that sticks to the tube. Now fill each 

 compartment almost full with distilled water, taking care that the 

 contents of either compartment does not flow into the other. Take 



