589 



Smith, G. Elliot (1895), The comparative anatomy of the cerebrum of 



Notoryctes typhlops. Transact. R. Soc. So. Australia, 1895. 

 — ('1900), Notes on the brain of Macroscelides and other Insectivora. 



Journal of Linnean Soc. London, 1900. 

 (1903), Further Observations on the Natural Mode of Subdivision of 



the Mammalian Cerebellum. Anat. Anz., Bd. 23, 1903. 

 Stirling, E. C. (1891), Description of a new Genus and Species of 



Marsupialia, Notoryctes typhlops. Transact. Roy. Soc. South Australia, 



1891. 

 ViCTORiN, J. F. (1860), Zoologiska anteckningar under en resa i Caplandet. 



Svenska Vet. Akademiens Handl., 1860. 

 Ziehen, Th. (1897), Das Zentralnervensystem der Monotremen und 



Marsupialier. Teil I. Denkschriften der Med.-naturw. Gesellschaft 



zu Jena, Bd. 5, 1897. 



Nachdruck verboten. 



Oll the Structure of the Erythrocyte. 



By E. A. Schäfer, Edinburgh. 



1. As to the existence of a membrane. From the time 

 of the announcement of the cellular structure of plants and animals 

 by ScHLEiDEN and Schwann in 1837—38 down to the year 1861 the 

 behef was general that every cell in the animal body possesses a definite 

 membranous envelope enclosing the cell - contents : animal cells being 

 in this respect strictly comparable to plant cells, in the majority of 

 which it was possible easily to demonstrate an enclosing membrane. 

 But in the year mentioned there appeared two papers on the animal 

 cell in which the authors ^) showed that the existence of such a mem- 

 brane as had been assumed is not essential to the idea of the cell, 

 since there are numerous typical cells in which nothing comparable to 

 the cellulose envelope of the plant cell can be shown to exist, and 

 would indeed, if it existed, be incompatible with the performance of 

 the functions which characterize many cells. 



The effect of this demonstration was far reaching and led to a 

 complete change in the definition a cell, the cell-membrane being now 

 omitted from the description (except in certain cases such as the ovum 

 in which the existence of a membrane is obvious) and the cell being 

 now defined as consisting essentially of protoplasm containing a nucleus. 



1) E. Brücke, Die Elementarorganismen. Wiener Sitzungsber., 

 Bd. 44, 1861. — M. Schultzb, Ueber Muskelkörperchen etc. Arch. f. 

 Anat. u. Physiol., 1861. 



