RED CORPUSCLES, 111 



shortly after removal from the vessels, there exudes from the 

 corpuscles an adhesive substance which smears their surface 

 and causes them to stick together. Of course the tendency 

 is to adhere by their flat surfaces. In examining a specimen 

 of blood under the microscope, the presence of this adhesive 

 exudation may be demonstrated by employing firm and 

 gradual pressure on the glass cover, when the adherent cor- 

 puscles may be separated in some instances, and with oblique 

 light we can sometimes see a little transparent filament be- 

 tween them, which draws them together, as it were, when 

 the pressure is removed. This phenomenon is due to a post 

 mortem change, but it occurs so soon, that it presents itself in 

 nearly every specimen of fresh blood which we examine, and 

 is therefore mentioned in connection with the normal charac- 

 ters of the blood-corpuscles. 



Dimensions. The diameter of the blood-corpuscles has a 

 more than ordinary anatomical interest ; for, varying perhaps 

 less in size than in other anatomical elements, they are rather 

 taken as the standard by which we form an idea of the size 

 of other microscopic objects. The diameter usually given is 

 sTTf o- f an inch. The exact measurement given by Eobin is 

 .0073 of a millimetre 1 or ^T sr of an inch. It is stated by 

 some authors that the size of the corpuscles is very variable, 

 even in a single specimen of blood. I have repeatedly 

 measured them with the eye-piece micrometer of Nachet, 

 and found a diameter of ^jVo- f an inch. Yery few are to 

 be found which vary from this measurement. Kolliker, who 

 gives their average diameter as 3-^0- of an inch, states that 

 " at least ninety-five out of every hundred corpuscles are of 

 the same size." 2 



We cannot leave the subject of the size of the blood-cor- 

 puscles without a notice of the measurements in the blood of 



1 LOC. at. 



2 KOLLIKER, Manual of Microscopic Anatomy r , London, 1860, p. 519. 



