Physiology. — The Significance of the concentration of calcium- 
ions for the movements of the stomach caused by stimulation 
of the N. Vagus’. By R. Brinkman and Miss E. van Dam. 
(Communicated by Prof. H. J. HAMBURGER). 
(Communicated at the meeting of December 18, 1920). 
The great significance of the calcium-ion as an antagonist of the 
Na- and K-ions has been set forth by numerous researches *) since 
the fundamental experiments by Rineer and Logs. The physico- 
chemical explanation of the action of calcium-ions must be sought 
in the balancing effect that this ion has towards the monovalent 
Na- and K-ions, as is very clearly illustrated, for instance, by the 
researches of NrvscHLosz’), published but latily, about the influence 
of salt-equilibration on the surface-tension of lecithine-soles in water. 
From the table below one can form an idea of this action. In this 
list it is stated how the strongly-increasing influence which definite 
(physiological) NaCl-concentrations exercise on the surface-tension 
TABEL I. 
cena mac LRE EEN EEE Cale CS a Eh | hn ah 
1 mol. 90.3 | 89.4 83.8 80.3 7618's nnNe | 82.7 88.8 
Il, mol. SO 90.3 84.4 80.8 16.6 78.4 83.6 90.6 
4 mol. 92.9 90.8 85.6 81.7 76.8 19.4 84.4 91.5 
'/g mol. 94.5 oii 86.1 82.1 76.4 80.0 85.2 92.4 
‘he mol. 92.9 89.7 84.4 81.2 76.0 79.8 | 84.9 91.0 
"39 mol. 87.6 89.0 84 80.5 75.9 19.6 83.3 90.3 
'/g4 mol. 83.6 88.3 83.6 80.1 75.7 78.5 82.5 89.4 
1128 mol. 80.1 87.5 821 | 78.5 | 75.9 11.5 81.9 88.1 
1) Summary in Héser: Physikalische Chemie der Zelle und Gewebe, Kap. 
VIIL (1914); v. TscHeRMAK: Allgemeine Physiologie, p. 120 (1916); Bayurss: 
Principles of General Physiology, p. 215 (1915); Héper: Pflüger's Archiv. 166, 
581, 1917. 
2) NeuscnLozs: Pflüger's Archiv. 181, 17, 1920. 
