Elementary hæmatology : a handbook for students and practitioners / by W.E. Cooke.

  • Cooke, W. E. (William Edmund), 1881-1939
Date:
1928
Catalogue details

Licence: In copyright

Credit: Elementary hæmatology : a handbook for students and practitioners / by W.E. Cooke. Source: Wellcome Collection.

    21/120 page 9
    of normal blood as a standard. The coagulation time of the tube which clots first is the prothrombin time. The “prothrombin quotient” is found by dividing the time of the unknown blood by that of the normal standard. Reticulated Red Cell Count.—The stain is made by adding two drops of a 2 per cent, potassium oxalate solution and one drop of a 1 per cent, aqueous solution of brilliant cresyl blue to 5 c.c. of 0*85 saline. Take up blood in the pipette for counting leucocytes to the 0*5 mark and draw up the solution to the 11 mark. Shake the pipette for two or three minutes and place a drop on a slide, spread and allow to dry, and examine with a 2 mm. objective. The percentage of reticulated cells in 1000 erythrocytes is calculated. Preparation of Blood Films.—The first essential in making a satisfactory blood film is to render the slides fat free. This is done by placing them in a mixture of chromic acid one part, strong sulphuric acid eight parts, for twenty-four hours; thoroughly wash under the tap and transfer them to a mixture of alcohol and ether. They are dried with a cloth rendered fat free by boil¬ ing in sodium carbonate solution and rinsed in several changes of water and dried, but not ironed. The Spreader.—A spreader may be made by cutting an ordinary Bxl microscope slide in half, or a special spreader 1 used. The spreader is a piece of glass measur¬ ing 5 cm. by 19 mm., the edges of which are very finely ground and square (fig. 5). A drop of blood the size of a large pin-head is placed half an inch from the end of a slide ; the spreader is held at an angle of approxi¬ mately forty-five degrees and moved backwards until it touches the drop ; the motion is then reversed, the spreader drawing the blood behind it and distributing 1 Made by Watson & Sons, 313 High Holborn.
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