STUDY OF THE HUMAN BLOOD-CORPUSCLES 



9 



The coloured blood-corpuscles. Under the microscope the blood is 

 seen to consist of a clear fluid (plasma], in which are suspended the blood- 

 corpuscles (fig. 5). The latter are of two kinds : the red or coloured 

 (r, r'), which are by far the most numerous, and the white, pale, or 

 colourless (p, g), which from their occurrence in the lymph are also 

 known as lymph-corpuscles. When seen singly the coloured corpuscles 

 are not distinctly red, but appear of a reddish-yellow tinge. In the 

 blood of man and of all other mammals, except the Camelidfe, they 

 are biconcave circular disks. Their central part usually has a slightly 

 shaded aspect, under the ordinary high power (fig. 6, 1), but this is due 

 to their biconcave shape, not to the presence of a nucleus. They have 

 a strong tendency to become aggregated into rouleaux and clumps when 

 the blood is at rest, but if it is disturbed they readily become separated. 



If the density of the plasma is increased in any way, as by evapo- 

 ration, many of the red corpuscles become shrunken or crenated (c). 



The average diameter of the human red corpuscles is>>0 v 077 milli- 

 meter (about ^oVo inch). 1 



There are from four to five millions of coloured corpuscles in a cubic 

 millimeter of blood. 



The colourless corpuscles of human blood are a little larger than 

 the coloured, measuring O01 mm. (o-^V^ inch) in diameter. They 

 are far fewer, numbering not more than ten thousand in a cubic 

 millimeter. Moreover they are 

 specifically lighter, and tend to 

 come to the surface of the prepara- 

 tion. If examined soon after the 

 blood is drawn, they are usually 

 spheroidal in shape, but they soon 

 become irregular (fig. 5, p, g), and 

 their outline continually alters, 

 owing to the amoeba-like changes 

 of form to which they are subject. 

 Some of the colourless corpuscles 

 are very pale and finely granular, 

 others contain coarser and more 

 distinct granules in their proto- 

 plasm. The protoplasm may also 

 contain clear spaces or vacuoles, 

 and a reticular structure is described 

 in it by some histologists. Each pale corpuscle has one or more 

 nuclei, which are difficult to see without the aid of reagents. 



In the clear fluid in which the corpuscles are suspended, a network 

 of fine straight intercrossing filaments (fibrin) soon makes its ap- 

 pearance (fig. 7). There are also to be seen a certain number of 



1 The following list gives the diameter in parts of a millimeter of the red blood- 

 corpuscles of some of the common domestic animals : Dog, 0-0073 ; rabbit, 0'0069 ; 

 cat, 0-0065 ; sheep, 0-0050 ; goat, 0-0041. 



FlG - "--FIBRIN-FILAMENTS AND BLOOD- 



TABLETS. 



A , network of fibrin shown after waghiug away 



the corpuscles from a preparation of blood that 

 has been allowed to clot ; many of the filaments 



radiate from small clumps of blood-tablets. 



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