WHITE BLOOD-CORPUSCLES. 



77 



ance, they are circular and nearly spherical, about -g-sVir f 

 an inch in diameter (fig. 29). They have a greyish, 

 pearly look, appearing variously shaded or nebulous, the 

 shading being much darker in some than in others. They 

 seem to be formed of protoplasm (p. 19), containing 

 granules which are in 



some specimens few and J'fy. 29.* 



very distinct, in others 

 (though rarely) so nu- 

 merous that the whole 

 corpuscle looks like a 

 mass of granules. 



These corpuscles can- 

 not be said to have any 

 true cell- wall. In a few 

 instances an apparent 

 cell-membrane can be 

 traced around them; 

 but, much more commonly, even this is not discernible till 

 after the addition of water or dilute acetic acid, which 

 penetrates the corpuscle, and lifts up and distends what 

 looks like a cell- wall, to the interior of which the mate- 

 rial, that before appeared to form the whole corpuscle, 

 remains attached as the nucleus of the cell (fig. 29). 



A remarkable property of the white corpuscles, first 

 observed by Mr. Wharton Jones, consists in their capa- 

 bility of assuming different forms, irrespective of any 

 external influence. If a drop of blood be examined 

 with a high microscope power under conditions by which 

 loss of moisture is prevented, at the same time that the 

 temperature is maintained at about the degree natural to 

 the blood as it circulates in the living body, the leu- 





* Fig. 29. Red and white blood-corpuscles. a, White corpuscle of 

 natural aspect, b, Three white corpuscles acted on by weak acetic acid. 



c, Red blood corpuscles. 



