A NEW METHOD OF COUNTING THE BLOOD-PLATELETS FOR CLINICAL PURPOSES

Abstract

A number of methods¹have been employed for estimating the number of blood-platelets per cubic millimeter of blood, but none of them has seemed to us practical or satisfactory for clinical purposes. A new method has therefore been devised, and it is as follows: The blood is mixed with a diluting fluid in the proportion of 1 to 100 by means of the pipette used for counting red blood-corpuscles, and the counting is done in an ordinary blood-counting chamber with a high power dry objective. In order to render the platelets more clearly visible, the specially thin cover-glass of Zeiss, with central excavation, is used (cover-glass No. 146, Zeiss catalogue). This may be obtained from Eimer & Amend, 205 Third Avenue, New York. The diluting fluid consists of two parts of an aqueous solution of "brilliant cresyl blue" (1:300) and three parts of an aqueous solution of potassium cyanid