THE BLOOD. 



107 



inch diameter 



ated into liquor sanguinis and corpuscles, or into defibriii- 

 ated blood and fibrin, or, lastly, into serum and a coloured 

 clot consisting of the fibrin with the corpuscles entangled in it. 



76. When blood is examined microscopically it is seen to 

 contain two kinds of corpuscles, the coloured kind already 

 alluded to, and a less numerous set of white corpuscles. 



The coloured or red corpuscles are, properly speaking, deep 

 orange, as may be seen by streaking blood on a white sur- 

 face. They are disc-shaped bodies, about 

 in man, circular, and flat or somewhat 

 concave on each side. They are clear, 

 and in mammals are destitute of nucleus; 

 but this is a mammalian peculiarity, 

 for in all other vertebrate animals they 

 have a nucleus and are oval. In. the 

 camel tribe they are likewise oval, but 

 are destitute of nucleus as in other 

 mammals. In different vertebrate ani- 

 mals the red corpuscles differ greatly 

 in size, as indeed do other textural ele- 

 ments. Their size is dependent more 

 on the affinities of the animal than on 

 its bulk. In ruminants generally they 

 are small; and in the smallest ruminant, 

 the musk deer, their diameter is only 



Fig. 61. BLOOD COR- 

 PUSCLES OF FROG, viz., 

 four red corpuscles 

 seen in full view, one 

 in profile, and one 

 white corpuscle. 



12 a 2 -5 of an inch. In birds they are smaller than in reptiles ; 

 and those of greatest size are found in the amphibia, the 

 largest known being those of the proteus, which are -^^ of an 

 inch in length. 



Hed corpuscles contain a firm framework or stroma, 

 besides their coloured contents; but it is difficult to believe 

 that they have any envelope, when one sees the great power 

 of elongation which they have in threading their way through 

 narrow passages, and the changes of shape which they under- 

 go in various circumstances outside the body, without ex- 

 posure of a membrane. They may often be seen to become 

 indented round the edges; and the processes between the 

 indentations may grow to a length which seems inconsistent 

 with the supposition that they are firmer toward the surface 

 than within. 



