A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . Fig. 7t>3.—Position of Hands xa Shaking Mixer. counting well (Fig. 764). The drop should not (1)flow into the well, (2) or contain air bubbles, or(3) particles of dirt. The cover shp is lowered untilthe fluid touches it, then the forceps is opened andwithdrawn with a jerk as in laying the cover sUpsfor fresh specimen (see Fig. 748). Air bubbles maybe avoided by obser\-ing the foregoing precautions. By holding the slide up to the light oti a level withthe eye and
A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . Fig. 7t>3.—Position of Hands xa Shaking Mixer. counting well (Fig. 764). The drop should not (1)flow into the well, (2) or contain air bubbles, or(3) particles of dirt. The cover shp is lowered untilthe fluid touches it, then the forceps is opened andwithdrawn with a jerk as in laying the cover sUpsfor fresh specimen (see Fig. 748). Air bubbles maybe avoided by obser\-ing the foregoing precautions. By holding the slide up to the light oti a level withthe eye and making pressure with the point of the for-ceps upon the cover shp, a series of varicolored con-centric rings wiU be seen about the point of the forceps?where it touches the glass. These are the Xewtonsrings, which are seen onlj- when two pieces of glassare in perfect apposition, when there are no dustparticles, etc., between them. The presence of theserings is therefore an e^?idence that the glasses are per-. FiG. 764.—Blowing Drop from Mixer on to Stage. fectly clean. Two to three minutes are now allowedfor the corpuscles to sink through the depth of one-tenth of a miUimeter and rest on the mapped-outbottom of the well. By at once obser^•ing the slideunder the microscope this sinking process may be are now ready to count; the lowest-power lens ofthe Leitz or Zeiss microscope may be used. Thistakes in its field of ^?ision the whole counting area, but 168 magnifies the corpuscles so shghtly that the strainupon the ej-e is great (see Plate XIII., Fig. 2). The7 or 9 objective of the Leitz takes in only J; of thecounting area, but does not strain the eye, and istherefore preferable, as with little practice the stagemaj be gradually moved until the whole area hasbeen examined (see Plate XIII., Fig. 4). As theproportion of white corpuscles to red is about 1 to700, there will be in a given area much fewer whitecorpuscles than red; and in the one-tenth of a cubicmil
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Keywords: ., bookauthorbuckalbe, bookcentury1900, bookdecade1910, bookyear1913
