SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 443 



gestalt der roten Bliitkurperchen die einer Glocke mit ziemlich 

 dicken Wandungen . . . ." This shape he compared to a 

 cup (Becker), bowl (Napf), medusa, or gastrula. Identical 

 results were reported from a series of mammals including a 

 macacus monkey. 



Weidenreich next asked (p. 468): ''Wie kommt es aber nun, 

 dass man sich bisher liber die wahre Form so tauschen konnte?" 

 Examining blood in 0.9 per cent sodium chloride solution he 

 found discs exclusively; in 0.6 per cent solution cups were seen 

 almost without exception. He concluded that saline solutions 

 exert a pure osmotic effect on the blood corpuscles; in higher 

 concentrations the corpuscles give up water thereby becoming 

 discoidal or crenated, in lower concentrations they imbibe water 

 and change to the cup or spheroidal condition. Since typical 

 cups are found in 0.65 per cent saline solution he considers this 

 to be isotonic with the blood of man and mammals. 



Weidenreich therefore believed he was in a position to account 

 for the alleged popular misconception concerning the true shape 

 of these elements (p. 469) : 



Nun wird aber verstandlich, wie die Tauschung iiber die wahre 

 Form moglich ist. Operirt man nicht sehr rasch bei der Untersuchimg 

 des unverdiinnten Bliites und benutzt man namentlich kaltere Ob- 

 jekttrager und Deckglaser, so geniigt die erhobte Verdimstung der 

 warmen Blutfllissigkeit, um eine starkere Konzentration des Serums 

 herbeizufi'ihren ; aber schon eine Schwankung des Kochsalzgehaltes 

 um 1 00 reicht wiederum hin, um eine Gestaltsveranderung der 

 Blutkorperchen auszulosen. Verhindert man also die Wasserabgabe 

 des Blutes durch Verdunstung in der oben geschilderten Weise, dann 

 erhalt man auch die richtige Glockenform. 



. In 1903 .Weidenreich learned of the recent careful freezing 

 point determinations which showed conclusively that the blood 

 is isotonic with ca. 0.9 per cent sodium chloride solution instead 

 of; 0.6 per cent as he believed. Hence he was forced to retract his 

 former view and conclude that the shape of the corpuscle is not 

 exclusively dependent on the osmotic pressure of the examining 

 medium. 



In the same contribution he presented an hypothesis designed 

 to harmonize his previous conclusions with certain well estab- 



