24 METHODS OF EXAMINATION 



of the body weight in kilograms and varied between 0.57 and 

 0.95%. Douglas found that the same method can be readily ap- 

 plied to animals. He found the volume of blood in male rabbits 

 to be 4.85% of the body weight in grams, varying in seven cases 

 between 6.09 and 4.2% and in female rabbits 5.32% of the body 

 weight, varying in four cases between G.28 and 3.71%. The 

 oxygen capacity per 100 grams body weight he found to be 0.70(3 

 cc. in the buck, varying between 0.968 and 0.577 cc, and 0.739 cc. 

 in doe rabbits, varying between 0.825 and 0.596 cc. 



THE RELATIVE VOLUME OF CORPUSCLES AND OF PLASMA 



The hematocrit as modified by Daland consists of a horizontal 

 armature carrying two capillary tubes to be placed on the shaft 

 of a centrifuge in place of the armature carrying the urine tubes. 

 The capillary tubes of the hematocrit are each graduated in 100 

 degrees and are held in place by springs. One of the tubes is filled 

 with water and placed in the armature, the other tube is filled 

 with blood by touching one end to a large drop of blood and hold- 

 ing the tube horizontally or the other end somewhat depressed. 

 It is at once placed in the armature with the zero end outward. 

 The tubes are revolved at a speed of 8000-10,000 per minute for 

 three minutes, by which time the column of red corpuscles will be 

 found unchangeable. The volume of red corpuscles is read easily, 

 the tubes having a lens front. If the blood cannot be centrifuged 

 at once it must be diluted. Daland used a 2.5% aq. soln. of potas- 

 sium dichromate, mixing the blood with an equal volume of dilut- 

 ing fluid. This is done, using the red pipette, by drawing blood 

 to the mark 1, then a small air bubble, then an equal volume of 

 diluting fluid, then another small air bubble and so on until three 

 or four tube lengths are obtained. The blood and diluting fluid 

 should be mixed at once by gentle shaking, care being taken not 

 to produce air bubbles. Both capillary tubes are to be filled with 

 the diluted blood and centrifuged as with fresh blood. The result 

 inns! be nmlt [plied by two. This method seems to be sufficiently 

 accurate for determining the relative volume of corpuscles and 

 plasma, excepting in cases of leukemia or extreme lcucocytosis, 

 when enough leucocytes are entangled with the red corpuscles to 

 make the result unreliable. 



