SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 463 



the burden of proof rests on those who have used anesthetized 

 animals (and apparently most previous workers have done so) 

 to show that the anesthetic held in the blood is not responsible 

 for the preponderance of cups observed. 



3. Action of fixatives 



Many workers have recorded that mammalian tissues pre- 

 served in various standard fixatives contain cup-shaped erythro- 

 plastids. Those who uphold the normality of the cup have laid 

 great stress on this line of evidence particularly in view of the 

 fact that '^in well preserved tissues of all sorts, and with all 

 fixatives such as are relied upon to reveal the structure of other 

 tissues,' the mammalian erythrocytes are typically cup-shaped" 

 (Lewis) . 



Smear preparations, such as advocated by Weidenreich, would 

 hardly seem to furnish reliable data concerning the moderately 

 flexed saucer shapes which are held by these workers to be the 

 normal intravital form. It is necessary that the corpuscles be 

 observed more ot less on edge. 



An examination of what is ordinarily called well-preserved 

 mammalian tissues demonstrates convincingly that the cup 

 shapes are indeed preponderatingly abundant within the ves- 

 sels. ^^ With Jordan ('09), however, I must deny the univer- 

 sality of this statement. Occasionally tissues have been observed 

 in which the corpuscles seen were discs almost exclusively. Not 

 only have cups and discs been observed within the same vessel, 

 but rarely vessels, have been found side by side, one containing 

 cups, the other discs. 



I have fixed small pieces of human vascular fat, obtained fresh 

 from operations, in 1 per cent osmic acid, in saturated subli- 

 mate in 0.75 per cent sodium chloride, and in the fluids of Zen- 

 ker, Orth and Helly. In each case only a few moments elapsed 

 between the removal of the tissue and its immersion in the fixa- 

 tive. Celloidin sections showed constantly a great preponder- 

 ance of cups. 



^* Sites must of course be chosen where the corpuscles are well separated. 



