BLOOD-GLOBULES. 



215 



Fie. 



THE SAME, seen a little within the focus. 



When beyond the focus, the globules will be seen with a bright 

 rim and a dark centre. (Fig. 55.) When within it they will appear 

 with a dark rim and a bright 

 centre. (Fig. 56.) 



The blood-globules accord- 

 ingly have the form of a 

 thickened disk with rounded 

 edges and a double central 

 excavation. They have, con- 

 sequently, been sometimes 

 called " blood-disks," instead 

 of blood -globules. The term 

 'disk/' however, does not in- 

 dicate their exact shape, any 

 more than the other; and 

 the term "blood-corpuscle." 

 which is also sometimes used, 

 does not indicate it at all. 

 And although the term "blood-globule" may not be precisely a 

 correct one, still it is the most convenient ; and need not give rise 

 to any confusion, if we remember the real shape of the bodies de- 

 signated by it. This term will, consequently, be employed when- 

 ever we have occasion to 

 speak of the blood-globules 

 in the following pages. 



Within a minute after being 

 placed under the microscope, 

 the blood-globules, after a 

 fluctuating movement of 

 short duration, very often 

 arrange themselves in slight- 

 ly curved rows or chains, in 

 which they adhere to each 

 other by their flat surfaces, 

 presenting an appearance 

 which has been aptly com- 

 pared with that of rolls of 



m, . . ,,-, BLOOD-GLOBULES adhering together, like rolls 



coin. This is probably ow- of coin> 



ing merely to the coagulation 



of the blood, which takes place very rarjidly when it is spread out 



in thin layers and in contact with glass surfaces ; and which, by 



Fig. 57. 



