RED GLOBULES OF THE BLOOD. 



245 



Fig. 78. 



low the level of the fluid. It thus becomes brighter as the object- 

 glass is carried downward, and the object falls within its focus. An 

 alternating appearance of the 

 blood-globules may, therefore, 

 be produced by viewing them 

 first beyond and then within the 

 focus of the instrument. When 

 beyond the focus, the globules 

 will be seen with a bright rim 

 and a dark centre (Fig. 77). 

 When within it, they will appear 

 with a dark rim and a bright 

 centre. (Fig. 78.) 



Within a minute after being 

 placed under the microscope, 

 the blood-globules, after a fluc- 

 tuating movement of short du- 

 ration, often arrange themselves 

 in slightly curved rows or chains, 

 in which they adhere to each 

 other by their flat surfaces, presenting an appearance which has been 

 aptly compared with that of rolls of coin. This is probably owing to 

 the coagulation of the blood, 

 which takes place very rapidly 

 when spread out in thin layers 

 and in contact with glass sur- 

 faces ; and which, by compress- 

 ing the globules, forces them 

 into such a position that they 

 occupy the least possible space. 



The color of the blood-glob- 

 ules, when viewed by transmit- 

 ted light and in a thin layer, is 

 a light amber or pale yellow. 

 It is deep red when seen by re- 

 flected light, or in thick layers. 

 The blood-globules have a con- 

 sistency which is very nearly 

 fluid They are exceedingly 



a .. . ~ RED GLOBULES OP THE BLOOD, adhering 



flexible, and easily elongated, together, like roils of coin, 



bent, or distorted by pressure 



in passing through the narrow currents of fluid which often establish 

 themselves in a drop of blood under microscopic examination ; but re- 

 gain their original shape as soon as the pressure is taken off. 



So far as immediate observation can show, the red globules of the 

 blood, in man and the mammalians, are homogeneous in structure. The 

 most careful examination fails to show, with any certainty, the evidence 



THE SAME, seen a little within the focus. 



Fijr. 79. 



