j6 Stiles and J 0 rgensen. — Studies in Permeability. IV. 
6 . It is impossible to find a critical concentration of a solution below 
which exosmosis of electrolytes will not take place. 
7 . Each of the assumptions leading up to Czapek’s theory of the 
plasma membrane is discussed, and it is shown that none of them can 
be accepted. 
8 . An attempt has been made to deduce a mathematical expression 
connecting time and exosmosis, and it is shown that the curve representing 
the equation so obtained from theoretical considerations is of an exactly 
similar form to those obtained in actual experiments. 
Imperial College of Science and Technology, 
South Kensington, S.W. 
September , 1916. 
Literature cited. 
1 . Czapek, F. : Versuche iiber Exosmose aus Pflanzenzellen. Berichte d. deut. Bot. Ges., xxviii, 
i 9 IO > PP-. i 59 " 6 9 - 
2. : Uber die Oberflachenspannung und den Lipoidgehalt der Plasmahaut in lebenden 
Pflanzenzellen. Berichte d. deut. Bot. Ges., xxviii, 1910, pp. 480-7. 
3 . : Uber eine Methode zur direkten Bestimmung der Oberflachenspannung der Plasma- 
haut von Pflanzenzellen. Jena, 1911. 
4 . : Weitere Beitrage zur Physiologie der Stoffaufnahme in die lebende Pflanzenzelle. 
I. fiber die Annahme von Lipokolloiden in der Plasmahaut. Internat. Zeitschr. fur phys.- 
chemische Biologie, i, 1914, pp. 108-23. 
5 . Jones, H. C., and Collaborators : The Conductivities, Dissociations, and Viscosities of 
Solutions of Electrolytes in Aqueous, Non-Aqueous, and Mixed Solvents. Washington, 
I 9 I 5 * 
6. Koltzoff, N. K. : Zur Frage der Zellgestalt. Anat. Anzeiger, xli, 1912, pp. 183-207. 
7 . Schryver, S. B. : Investigations dealing with the State of Aggregation of Matter. Parts I— III. 
Proc. Roy. Soc., B, lxxxiii, 1910, pp. 96-123. 
8. : Investigations dealing with the Phenomena of * Clot ’ Formations. Part II. 
The Formation of a Gel from Cholate Solutions having many Properties analogous to 
those of Cell Membranes. Proc. Roy. Soc., B, lxxxvii, 1914, pp. 366-74. 
9 . and Hewlett, M. : Investigations dealing with the Phenomena of 1 Clot ’ 
Formations. Part IV. The Diphasic Erosive Action of Salts on the Cholate Gel. Proc. 
Roy. Soc., B, Ixxxix, 1916, pp. 361-72. 
10 . Stiles, W., and Jorgensen, I. : Studies in Permeability. I. The Exosmosis of Electrolytes 
as a Criterion of Antagonistic Ion- Action. Ann. of Bot., vol. xxix, 1915, pp. 347-67. 
11 . Vernon, H. M. : Die Rolle der Oberflachenspannung und der Lipoide fur die lebenden Zellen. 
Bioch. Zeitsch., li, 1913, pp. 1-25. 
