78 ENUMERATION OF BLOOD CORPUSCLES. [BOOK I. 



and solution in the glass jar. (5) A brass stage plate, carrying a glass 

 slip, on which is a cell, i of a millimetre deep. The bottom of this is 

 divided into -f^ millimetre squares. Upon the top of the cell rests the 

 cover-glass, which is kept in its place by the pressure of two springs 

 proceeding from the ends of the stage plate. 



" Various diluting fluids l have been recommended in order to change 

 as little as possible the aspect of the corpuscles. It is not well, however, 

 to observe the characters of the corpuscles during the numeration. What- 

 ever solution be employed, the corpuscles are more or less changed by it. 

 One which answers very well is a solution of sulphate of soda in distilled 

 water, of a specific gravity of 1025. 



"The mode of proceeding is extremely simple. 995 cubic millimetres of 

 the solution are placed in the mixing jar ; 5 cubic millimetres of blood are 

 drawn into the capillary tube from a puncture in the finger, and then blown 

 into the solution. The two fluids are well mixed by rotating the stirrer 

 between the thumb and finger, and a small drop of this dilution is placed 

 in the centre of the cell, the covering glass gently put upon the cell, 

 and secured by the two springs, and the plate placed upon the stage of the 

 microscope. The lens is then focussed for the squares. In a few minutes 

 the corpuscles have sunk to the bottom of the cell, and are seen at rest on 

 the squares. The number in ten squares is then counted, and this multiplied 

 by 10,000 gives the number in a cubic millimetre of blood. 



" The average of healthy blood was decided by Vierordt and Welcker 

 to be 5,000,000 per cubic millimetres, and later results agree with this 

 sufficiently nearly to justify the adoption of this number as the standard, it 

 being remembered that in a healthy adult man the number may be a little 

 higher, in a woman a little lower." 



By employing the methods previously described the following 

 results have been obtained : 



Welcker found a cubic millimetre of the healthy blood of man to 

 contain 5,000,000 corpuscles. Malassez found the number to vary 

 between 4,000,000 and 4,600,000, the average being about 4,500,000. 



Malassez has determined the total number of corpuscles in the 

 blood of a variety of animals, and he has determined for each 

 the number of corpuscles corresponding to a unit weight (one 

 gramme) of the body. This number he proposes to designate as 

 the ' corpuscular capacity ' (' capacite globulaire ') of the blood. In 

 the case of man the corpuscular capacity amounts to 341,000,000, 



1 The following diluting solutions have been employed : 



a. A solution of sulphate of soda and distilled water of specific gravity 1025. 



b. Potain's Solution : Solution of gum acacia sp. gr. 1020. One volume. 

 Equal parts of sulphate of soda and chloride of sodium, in solution of specific 



gravity 1020. Three volumes. Mix. 



c. Keyes' Solution: 



" Take urine slightly phosphatic, easily obtainable after a meal, about 1020 sp. gr., 

 and make of it a saturated solution of borax. Clouds of earthy phosphates are thrown 

 down. Filtration yields a clear alkaline fluid of sp. gr. about 1030. Add water 

 enough to reduce the specific gravity to 1020, and the fluid is ready for use." 



