THK BLOOD. 



51 



Fig. 7. HUMAN BLOOD. MAGNIFIED ABOUT 1000 DIAMETERS. (After Schafer.) 

 r, r, single red corpuscles seen lying flat; r', r' , red corpuscles on their edge and 

 viewed in profile; r", red corpuscles arranged in rouleaux; c, c, crenate red corpuscles; 

 p, a finely granular pale corpuscle; g, a coarsely granular pale corpuscle. Both have two 

 or three distinct vacuoles, and were undergoing changes of shape at the moment of ob- 

 servation; in g, a nucleus also is visible. 



included in the explanation of the phenomena of coag- 

 ulation. 



THE RED COEPUSCLES OF THE BLOOD. 



1. Their Size and Form. The red corpuscles of human 

 blood are biconcave, circular disks having a diameter of 

 g-Toif inch. They have no definite membrane and are with- 

 out a nucleus. In fresh blood these corpuscles show a 

 tendency to run together in rows called rouleaux, the 

 reason for which is not definitely known. The peculiar 

 reflection of the light through the concave center gives to 

 them when viewed with a microscope the appearance of 

 having a nucleus. It is, however, a mere optical illusion. 

 The size of these corpuscles as a rule increases as we go 

 down the animal scale. The largest corpuscles are found 

 in the salamander-like proteus, in which they can be actu- 

 ally individually seen by the unaided eye. In Figure 8 

 there are indicated drawn to the same scale, the relative 

 sizes and forms of red corpuscles of several different ani- 



