SHAPE OF MAMMALIAN RED BLOOD CORPUSCLE 471 



Between the limits of form induced by a 0.3 per cent sodium 

 chloride solution and by mild crenation the shape of the red 

 corpuscles is repeatedly reversible. 



Indi^'idual variability exists in the response of erythroplastids 

 to diluting media; this is perhaps referable to diverse elastici- 

 ties of the corpuscular membranes. 



Undiluted drawn blood, and blood diluted with human serum, 

 show the red corpuscles to be biconcave discs. Human serum 

 must be diluted about one-third with water before ,the cup form 

 predominates. 



Freezing point determinations which show that mammalian 

 plasma is isotonic with a 0.9 per cent saline solution (instead 

 of 0.6 per cent) are roughly substantiated by such dilution 

 experiments. 



The study of circulatitig blood in non-anesthetized living 

 mammals corroborates the normality of the disc. 



The results gained by the use of fixatives, although seemingly 

 adverse to the disc view, may be satisfactorily interpreted in 

 terms of unequal fixation; this is supported by experiment. 



The several lines of evidence here presented seem to justify the 

 conclusion that the biconcave disc represents the normal shape of 

 the mammalian erythroplastid — the concavo-convex cup being merely 

 an occasional modification. 



F. BIBLIOGRAPHY 



Albrecht, E. 1904 Cytopathologische Mitteilungen. Verhandl. d. deutsch. 



Pathol. Gesell. Jahrg., Heft 1, pp. 88-94. 

 Arey, L. B. 1916 The mammalian erythrocyte — a biconcave disc. Science, 



n.s., vol. 44, no. 1133, pp. 392-395. 

 Brass, A. 1897 Atlas of human histology. Trans, by R. A. Young. Wm. 



Wood and Company, New York, 160 pp. 

 V. David, C. 1908 Ueber optische Einstellungsbilder kreisscheibenformiger 



Erythrozyten. Arch. f. mikr. Anat., Bd. 71, pp. 159-163. 

 Dekhuyzen, M. C. 1899 Becherformige rote Blutkorperchen ('Chromokra- 



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1901 tJber die Thrombocyten (Blutplattchen). Anat. Anz., Bd. 19, 



no. 21, pp. 529-540. 

 DujARDiN, F. 1842 Nouveau manuel de I'observateur au microscope. Li- 



brairie encyclopidique de Roret, Paris. 330 pp. 

 vox Ebner, V. 1902 Vom Gefasssystem. Koelliker's Handb. d. Gewebelehre 



d. Menschen. Englemann, Leipsig. Bd. 3, 1020 pp. 



