SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 447 



records that red corpuscles appear as cups when examined in 

 Ij^mph from the thoracic duct. 



In a later paper Lohner ('11) asserted that the cabinet did 

 not hamper his movements in the least, and rejoins concerning 

 the alleged role of evaporation (p. 102): ''Hier kommt man 

 jedenfalls mit dem Schlageworte Verdunstung nicht aus." 



Jordan ('09) examined drawn blood in ordinary preparations 

 and by means of sealed hanging drops on warmed slides. He 

 reports (p. 411) ''that the biconcave disc form preponderates in 

 numbers very generally in the hanging drop and that all varia- 

 tions from this shape can be interpreted in terms of pressure, 

 contact, or contraction." 



Recently Jordan ('15) has communicated his results with the 

 use of Hogan's ('15) normal salt gelatin mixture, it being 

 claimed that this solution simulates the colloidal constitution of 

 blood plasma. Blood was drawn into a drop of the mixture, and 

 a sealed depression slide preparation made in which air was 

 excluded (p. 168): ''A rapid preliminary examination revealed 

 not a single indubitable cup form. Careful searching may 

 discover a few cups in most preparations." The same tech- 

 nique applied to Tyrode's, Ringer's, and a 0.9 per cent salt solu- 

 tion gave essentially identical results. Cup forms were observed 

 most abundantly in ordinary preparations with Ringer's fluid, 

 the cover glass being supported by a hair (p. 169) : "The explana- 

 tion that immediately suggests itself is that the floating discs 

 become altered into cups through adjustment to the narrow 

 confines between slide and cover glass." 



2. Results from circulating blood 



Since blood may be observed intravitally in the transparent 

 parts of animals many extraneous complicating factors are 

 eliminated. 



Weidenreich ('02) records his observations (p. 468) : 



Ich wahlte zur Priifung am Icbenden Tiere ein Kaninchen; . . . . 

 Wenn die Stromung recht lel:)haft ist, gelingt as allerdings nur schwer, 

 ein einzelnes Korperchen schiirfer in's Auge zu fassen, bei Verlangsam- 

 ung des Stromes aber oder bei eingetretener Stagnation erkennt man 



