466 LESLIE B. AREY 



methods having for the most part been introduced in connection 

 with the previous section. 



We have seen that the examination of undiluted drawn blood 

 has led various workers to diametrically opposed conclusions. 

 Those who champion the cup form believe that a rapid trans- 

 formation of cups into discs, before preparation are made and 

 examined, is responsible for the finding of discs by slower mo- 

 tioned workers. The whole cup hypothesis, therefore, hangs on 

 the sudden secondary transformation of cups into discs when in 

 contact with the air. The reproach of slowness, which has 

 been repeated so frequently is, nevertheless, not incontestable 

 but is open to scrutiny and analysis. 



Two factors have been emphasized as responsible for the 

 alleged sudden mutation of shape. Weidenreich ('02) and Lewis 

 ('05; by implication) urged the necessity of maintaining normal 

 temperature if cups are to be seen: Weidenreich' s position was 

 obviously untenable (p. 452) and in his papers of '03, '05 a, and 

 '10 he abandoned his insistence on temperature as a causative 

 modifying agent. The second factor is that of evaporation 

 resulting in an effective concentration of the plasma, before 

 drawn blood is observed." By drawing in blood, as it issued 

 from the cut, between two parallel cover glasses fused at one 

 point, the exposure to air before examination was reduced to a 

 rhinimum (p. 452) yet I am not able to conclude that these ex- 

 periments support the cup theory. Lohner's ('10) tests w^ith his 

 constant-temperature and moisture-saturated cabinet (p. 446) 

 precluded evaporation, yet he obtained '^stets und ausschliess- 

 lich" biconcave discs. In the experiments in which I diluted a 

 droplet of blood in a large drop of human serum, without the 

 blood first coming in contact with air, the increased concentra- 

 tion of the mixture during the few seconds before the preparation 

 was sealed must have been negligible; when it is further dis- 

 covered (p. 457) that human serum must be diluted one-third to 

 obtain cups, the futility of the evaporation argument becomes 

 apparent. For these reasons I am unwilling to admit that the 

 evidence derived from undiluted drawn blood either establishes 

 or supports the normality of the cup. 



From the work of Ranvier in 1875 it has been known thai; 



