440 LESLIE B. AREY 



such forms have been seen and described since the days of the 

 pioneer microscopists. The issue, therefore, hinges entirely on 

 the determination of what is the normal intravital condition, 

 and what the modification or artefact. 



Wagner ('33, p. 4) was the first to appreciate and definitely 

 formulate this, our present contention: "Ob die menschlichen 

 Blutkornchen auf beiden Flachen platt oder konvex oder gar 

 konkav sind, oder konvex-konkav, wie wohl behauptet worden 

 ist liisst sich schwer ausmitteln .... 



Evidence as to the shape of the erythroplastid has been de- 

 rived from three sources: (1) drawn blood; (2) circulating blood; 

 (3) fixed tissues or smears. The results obtained previously in 

 each of these fields will first be considered separately. 



B. HISTORICAL 



1. Results from drawn hlood 



The desultory microscopical observations of Leeuwenhoek 

 (1719) included an examination of mammalian blood, he ap- 

 parently being the first to observe this tissue attentively. Blood 

 drawn from the finger was mixed with an aqueous decoction of 

 pareira brava, the resulting dilution facilitating its study. 

 Translated, his description (epistola 44, p. 422) is as follows: 

 " . . . . most of the corpuscles have- a certain concavity 

 or sinus receding into them, as if we have a vesicle full of water 

 and by pressure of the finger should indent the middle of the 

 vesicle as a pit or depression." 



Muys (1738), Fontana (1787), and Dujardin ('42) essentially 

 substantiated Leeuwenhoek's conclusion. It is evident, how- 

 ever, that the uncontrolled type of observation recorded by 

 Leeuwenhoek retains an historical interest only, for the action 

 of water in altering the shape of these corpuscles is a matter of 

 common knowledge, dating back to the time of Muys (1751). 



Schultze ('65) was the first to record the occurrence of some 

 spherical red corpuscles in drawn blood. Later, in 1877, Litten 

 examined the blood of severely anemic individuals and found 

 cup-like corpuscles which he described as 'pessary' forms; these 



