THE BLOOD. 



mass, named the clot or crassamentum of the blood, from which the serum 

 gradually separates. The relation between the above-mentioned constituents 

 of the blood in the liquid and the coagulated states may be represented by 

 the subjoined scheme : 



Liquid 

 blood 



Corpuscles . 



Liquor sanguinis 



Fibrin 



Scrum 



Clot 



Coagulated blood. 



Red Corpuscles. These are not spherical, as the name " globules," by 

 which they have been so generally designated, would seem to imply, but 

 flattened or disk-shaped. Those of the human blood 



Fig. XV, 



(fig. xv., lf 2 ) have a nearly circular outline, like a 



Fig. XV. RED COR- 

 PUSCLES OF HUMAN 

 BLOOD ; MAGNIFIED 

 ABOUT 500 DIAMETERS 

 (Wagner). 



1, shows depression 

 on the surface ; 2, a 

 corpuscle seen edgeways ; 

 3, red corpuscles altered 

 by exposure. 



piece of coin, and most of them also present a shallow 

 cup-like depression or dimple on both surfaces ; their 

 usual figure is, therefore, that of biconcave disks. 

 Their magnitude differs somewhat even in the same 

 drop of blood, and it has been variously assigned by 

 authors ; but the prevalent size may be stated at 

 from 3 3*0 ^ th to -g-gVo^ ^ an ^ nca * n diameter, and 

 about one-fourth of that in thickness. 



In mammiferous animals generally, the red cor- 

 puscles are shaped as in man, except in the camel 

 tribe, in which they have an elliptical outline. In 

 birds, reptiles, and most fishes, they are oval disks 

 with a central elevation on both surfaces (fig. xvi., 

 from the frog), the height and extent of which, as 

 well as the proportionate length and breadth of the 



oval, vary in different instances, so that in some osseous fishes the elliptical 

 form is almost shortened into a circle. The blood-corpuscles of invertebrata, 



although they (except in some of 



Fig. XVI. the red-blooded annelid es) want the 



red colour, are also, for the most 

 part, flattened or disk-shaped ; 

 being in some cases circular, in 

 others oblong, as in the larvas of 

 aquatic insects. Sometimes they ap- 

 pear granulated on the surface like 

 a raspberry, but this is probably due 

 to some alteration occurring in them. 

 The size of the corpuscles differs 

 greatly in different kinds of ani- 

 mals ; it is greater in birds than in 

 mammalia, and largest of all in the 

 naked amphibia. They are for the 

 most part smaller in quadrupeds 

 than in man ; in the elephant, 

 however, they are larger, being 

 gYQ^th of an inch, which is the 

 largest size yet observed in the blood-corpuscles of any mammiferous 



Fig. XVI. BLOOD CORPUSCLES OF THE FROG; 



MAGNIFIED ABOUT 500 DIAMETERS. 



1, shows their broad surface ; 2, one seen 

 edgeways ; 3, shows the effect of weak 

 acetic acid ; the nucleus has become distinct ; 

 4, a colourless or lymph corpuscle (from 

 Wagner). 



