NORMAL HJEMATOLOGY 129 



by the use of alcohol to remove the water, followed by ether, which 

 will evaporate quickly and remove the alcohol. 



Hydrogen peroxide oxidizes organic matter; alcohol and ether 

 coagulates. 



The cleaning fluids (hydrogen peroxide and water) are used by 

 filling the pipette and rolling it for a few minutes between the thumb 

 and fingers and then blowing or drawing the fluid out. 



In the use of the drying fluids (alcohol and ether) do not blow 

 the fluids out of the pipettes, as the moisture of the breath will defeat 

 the object which one is seeking. Having filled the pipette with 

 alcohol or ether, draw it into the rubber tube, remove the rubber 

 tube from the pipette, blow the fluid out of the rubber tube, replace 

 it upon the pipette, then draw air through the pipette. After using 

 alcohol in this way, followed by ether, one may be assured that the 

 pipette is absolutely dry. 



For the student's work, secure the blood from the lobe of the 

 ear or the side of the tip of the third finger. The ear is better, as 

 it contains fewer nerves, gives more blood, and will continue to bleed 

 for a longer time. The ear or finger should be lightly washed with 

 a towel moistened with distilled water, then dried with the towel to 

 remove any dirt or loose epithelial cells. The needle used should 

 be a fair-sized glover's needle. It is a three-sided needle, the sides 

 of which are so ground that each has a fine saw-edge and will cut 

 and not crush the tissues as a saddler's needle will. The needle 

 should be kept clean with distilled water and hydrogen peroxide, and 

 sterilized with alcohol. 



The puncture should be made by holding the lobe of the ear 

 between the thumb and finger and pricking lengthwise of the ear 

 in its lowest part. The needle should enter about one-quarter of 

 an inch, and should be thrust in quickly while the thumb and finger 

 hold the ear, and when withdrawn it should be given a half-turn 

 and be quickly removed. The first drop of blood should always be 

 wiped away to moisten the skin with blood, and also because it clots 

 quicker than the following drops. 



The blood should gradually ooze out of itself. It should never 

 be forcibly squeezed out by pinching, as that will give an abnormal 

 specimen; but the ear may be gently pressed an inch or so above 

 the puncture, to make the blood flow more freely. 



To fill a pipette by suction, take the lobe of the ear between the 

 thumb and finger of the left hand, standing behind and to the right 

 when using the right ear and in front and to the left when using 

 the left ear. Place the tip of the pipette upon the thumb that is 

 behind the ear hold the pipette with the right hand near its upper 

 extremity, with the marks showing in front; then, by turning the 

 thumb, insert the capillary point into the drop of blood and do riot 

 allow it to touch the skin of the ear; the column of blood drawn into 



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