Studies in blood-pressure : physiological and clinical . seen, consisting of closely-packed, minute images of the flame produced by thelongitudinal fibrillation of the glass. In the processof drawing out, the tube becomes minutely corrugatedor fibrillated in the direction of its axis. The corruga-tions are extremely small, but they are easily observedwhen a tube is held before a flame and the structureof the glass is examined by a pocket lens, when thecorrugations are seen to produce alternate bright andshaded lines disposed in the vertical direction. Eachcorrugation acts as a lens, hence the
Studies in blood-pressure : physiological and clinical . seen, consisting of closely-packed, minute images of the flame produced by thelongitudinal fibrillation of the glass. In the processof drawing out, the tube becomes minutely corrugatedor fibrillated in the direction of its axis. The corruga-tions are extremely small, but they are easily observedwhen a tube is held before a flame and the structureof the glass is examined by a pocket lens, when thecorrugations are seen to produce alternate bright andshaded lines disposed in the vertical direction. Eachcorrugation acts as a lens, hence the horizontal linemade up of a congeries of images of the flame. (6)When some fixing fluid (such as Hayems) is addedto blood, the mixture presents a certain degree ofopacity according to the amount of blood or of thefixing fluid, (c) The opacity thus produced completelyshuts out of view the illuminated line, until, on diluting227 228 APPENDIX further, a definite point is reached, when it can just bedetected as a streak of light across the tube—the dawn,. Fig. 8.—The , Blood measurer; V, mixing pipette; c, flattened graduated tube; d, mode ofholding the tube for observation. as it were, of the bright minute images of the flameSeen when the opacity is absent or is further reduced. THE H^MACYTOMETEE 229 Repeated observation has shown that the developmentof this delicate horizontal line by dilution with thefixing fluid is a very sensitive indicator of the percent-age of the blood corpuscles. The apparatus consists of (1) a graduated flattenedtube ; (2) an automatic blood measurer ; (3) a mixingpipette ; (4) a canclle ; and (5) a bottle of Hayemssolution 1 (see Fig. 8). The determination of the scale was made by theenumeration method extended to 120 squares appliedto the blood of normal man. One hundred degreespresents the generally accepted standard of 5,000,000corpuscles per mm. ; therefore 80 degrees is equivalentto 4,000,000, etc. The white corpuscles in a state
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