462 LESLIE B. AREY 



the flow selects one limb almost exclusively, separate corpuscles, 

 nevertheless, being intermittently 'kicked off' into the slowly 

 moving plasma of the other limb.^^ Such a situation, where the 

 current in the main vessel is rapid and normal (to find which 

 often necessitates considerable diligent search), I regard as most 

 favorable for study. Criticisms of pressure, agglutination, and 

 of observing vessels so small that the corpuscles must necessarily 

 adjust themselves to their exiguous confines are obviated. 



Erythroplastids emerging from the main stream one or two 

 at a time in the manner indicated were found to be discs; most 

 of these corpuscles are revolving when first seen and it is easy 

 to be certain of their biconcavity. In such situations I have 

 observed hundreds of discs with only an occasional cup- or sau- 

 cer-form;'^ this observation has been corroborated by several 

 of my colleagues. 



In anesthetized guinea-pigs and rabbits, cups were very com- 

 mon, and in a dog under ether anesthesia a great preponder- 

 ance of cup shapes was observed. The query immediately 

 presents itself whether under these conditions the anesthetic is 

 responsible for the cup shape. The following experiment is 

 highly suggestive: 



Experiment 1.4.1. Hanging drop preparations of human blood and 

 the blood of the cat, dog, guinea-pig, rabbit, and rat, diluted with 

 serum, were made. When a drop of ether or chloroform was now 

 introduced into the bottom of the life cell the drop took on the vapor 

 and the discs were seen to change rapidly through the various cup- 

 shapes to spheres, finally laking and becoming shadows. ^'^ 



I believe that my observations indicate that the erythroplas- 

 tids of normal circulating mammalian blood are biconcave discs ; 



^* For making these observations I can particularly recommend the dog. 



^^ Perhaps the number of cups is somewhat increased by the presence of cor- 

 puscles brought by the capillary net from regions of the omentum in stasis. 



1' A curious surface tension effect was obtained when corpuscles were re- 

 moved from a hanging drop of Tyrode's solution before the effect of the anes- 

 thetic had proceeded far. On transference of these cupped forms to a drop of 

 pure Tyrode they became discs whereupon some moved edge foremost across the 

 field with a wobbling motion for longer or shorter distances then turned abruptly 

 and continued at an angle. This would be repeated for some time. 



