WHITE COEPUSCLES. 



71 



gives it up again, are the chief means by which oxygen is 

 carried in the blood (see also p. 75). 



By heat, mineral and other acids, alkalies, &c., haemoglobin 

 is decomposed into an albuminous matter (resembling glob- 

 ulin) 'and hcematin. The latter, now known to be a product 

 of the decomposition of haemoglobin, was once thought to be 

 the natural coloring matter of the blood. 



The White Corpuscles of the Blood or Blood Leucocytes. 



The white corpuscles are much less numerous than the red. 

 On an average, in health, there may be one white to 400 or 

 500 red corpuscles ; but in disease, the proportion is often as 

 high as one to ten, and sometimes even much higher. 



In health, the proportion varies considerably even in the 

 course of the same day. The variations appear to depend 

 chiefly on the amount, and probably also on. the kind of food 

 taken ; the number of leucocytes being very considerably in- 

 creased by a meal, and diminished again on fasting. 



They present greater diversities of form than the red ones 

 do ; but the gradations between the extreme forms are so 

 regular, that no sufficient reason can be found for supposing 

 that there is in healthy blood more than one species of white 

 corpuscles. In their most general appearance they are circular 

 and nearly spherical, about ^^ of an inch in diameter (Fig. 

 29). They have a grayish, 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. 26), 

 containing granules which are 

 in some specimens few and 

 very distinct, in others 

 (though rarely) so numerous 

 that the whole corpuscle looks 

 like a mass of granules. 



These corpuscles cannot 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 di- 

 lute acetic acid, which pen- 

 etrates the corpuscle, and lifts 

 up and distends what looks * ed and wh * te Wood-corpuscles A, 



,.V 11 11 ,1 White corpuscle of natural aspect; B, 



like a Cell-Wall, tO the m- Three white corpuscles acted on by weak 

 terior of which the material, acetic acid, c, Red blood-corpuscles. 



FIG. 29. 



