SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 451 



preponderated. He concludes that fixation causes contraction, 

 which is probably unequal at the center and rim, thereby pro- 

 ducing cups. 



Lohner ('11) elaborated this latter view. The coagulation of 

 fixation involves a diminution in diameter. By experiment he 

 showed that when blood issues from a puncture of the skin into 

 a drop of fixative, or when it is drawn by capillarity into osmic 

 acid between two cover glasses, the conditions are present for 

 an unequal action of the fixative with a resulting distortion of 

 the corpuscles. Corpuscles meeting the fluid edge foremost 

 become wedge-shaped; when the flat surface is first fixed a cup 

 results. Discs are obtainable provided the fixation is uniform. 



Wiedenreich ('10) accused Lohner ('10) of being inconsistent 

 (p. 448), for in living animals he held cups to be illusions and in 

 drawn blood he considered them artefacts. Having observed 

 cups in a portion of excised mesentery, Weidenreich added fixa- 

 tive and still saw cups, which, he said, were not illusions, for if 

 squeezed from the vessels they retained the cup appearance. 

 Lohner ('11) interpreted this experiment as follows. In the 

 vessels there are discs which may give a deceptive appearance of 

 cups, as well as temporary cups due to distortions, and real cups. 

 The apparent cups were changed to artificial cups by the fixa- 

 tive; hence this form was seen when the corpuscles were pressed 

 from the vessels. 



It is evident from the foregoing resume that the normal shape 

 of the erythroplastid remains undetermined. The hope of ob- 

 taining new evidence on this fundamental question has induced 

 me to undertake the pr<&sent \Vork, concerning which a prelimi- 

 nary communication has already been published (Arey, '16). 



C. OBSERVATIONS 



1. Expeiimentation with drawn blood 



In ordinary preparations of undiluted blood, made as quickly 

 as possible and examined between warm slides and covers, I 

 have usually observed a few cups intermingled with large num- 

 bers of discs. The transformation of cups into discs, which 



