SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 467 



graded temperatures can alter disc-shaped corpuscles to deep 

 cups, thick- walled cups, or even to spheres, e.g., typical cups 

 are found exclusively when blood is warmed to 55° (Zoth). It 

 is impossible that some investigators who advocate the cup 

 shape have unduly heated their slides and covers (perhaps in 

 attempting to allow for cooling when warm stages were 

 not available) in overzealous attempts to maintain normal (!) 

 conditions. 



We have seen (p. 444) that Weidenreich, at a loss to reconcile 

 the cup shape of corpuscles in 0.6 per cent salt solution with the 

 disc shape in the well established isotonic 0.9 per cent first held 

 as responsible a decreased elasticity of the corpuscular mem- 

 brane in saline solutions; later he shifted the emphasis to a 

 hypothetical influence of a changed 'Molecularkraft' in the 

 solution due to the presence of colloids. Both the results of 

 Jordan ('15) with Hogan's normal salt-gelatin mixture and my 

 own in repeating Weidenreich's experiment are not in agreement 

 with the latter's conclusion; hence I believe that Weidenreich 

 is still confronted with his original dilemma. This conviction 

 is strengthened by the fact that when serum albumen was added 

 to normal saline and Tyrode's solutions in an amount which 

 duplicated the protein content of blood plasma, I obtained an 

 examining medium in which the corpuscles were unquestion- 

 ably discs. 



Since the results of freezing point determinations are not 

 accepted by those who champion the cup shape as giving reliable 

 information regarding the isotonicity of physiological salt solu- 

 tion (p. 443), it is evident that the use of artificial media alone 

 serves only to incite controversy. For these reasons much of 

 the work of Weidenreich and that of Lewis ('05) and Jordan 

 ('15) with respect to this point is in itself not crucial. If one 

 believes in the cup shape and is able to obtain this form only in 

 0.6 per cent instead of the accepted isotonic 0.9 per cent saline 

 solution, he of course can ever invoke the aid of extraneous fac- 

 tors to explain the discrepancy. The escape from this quandary 

 lies in using serum as the diluent. I have already given my 

 reasons (p. 460) for distrusting the data obtained from the use 

 of the rat, guinea-pig, and rabbit. Hence I must for the pres- 



