KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 



TE AMSTERDAM. 



PROCEEDINGS 



VOLUME XXI 

 N°. 9. 



President: Prof. H. A. LORENTZ. 

 Secretary: Prof. P. Zeeman. 



(Translated from : "Verslag van de gewone vergaderingen der Wis- en 

 Natuurkundige Afdeeling," Vol. XXVII). 



CONTENTS. 



H. P. BARENDRECHT: "Urease and the radiation-theory of enzyme-action", p. 1126. 



L. E. J. BROUWER: "Ueber topologische Involutionen", p. 1143. 



H. Zwaardemaker and F. Hooewind: "On the Photo-electricity of Gels", p. 1146. 



1. K. A. Wertheim SalomonsoN: "The measurement of Chronaxia", p. 1152. 



W. de SitteR: "Theory of Jupiter's Satellites. I. The intermediary orbit", p. 1156. 



J. WOLTJER Jr.: "On the perturbations in the motion of Hyperion proportional to the first power 



of Titan's eccentricity", i Communicated by Prof. W. DE Sitter), p. 1164. 

 J. A. SCHOUTEN and D. J. STRUIK: "On the connexion between geometry and mechanics in 



static problems' . (Communicated by Prof. H. A. LORENTZ', p. 1176. 

 J. J. VAN LAAR: "On the Equation of State for Arbitrary Temperatures and Volumes. Analogy with 



Planck's Formula". (Communicated by Prof. H. A. LORENTZ), p. 1184. 

 A. F. HOLLEMAN: "EYKMAN's Refractometric Investigations, in Connection with the Presentation of 



the Edition of his Works ', p. 1200. 

 F. E. C. SCHEFFER and G. MeijeR: "On an Indirect Analysis of Gas-Hydrates by a Thermodynamic 



Method and Its Application to the Hydrate of Sulphuretted Hydrogen", I. (Communicated by 



Prof. J. BÖESEKENi, p 1204. 

 H. NORT: "The distance-correction for the plates of the Harvard Map of the Sky". (Communicated 



by Prof. J. C. Kapteyn», p. 1213. 

 M. W. Beijerinck: "Oidium lactis, the milkmould, and a simple method to obtain pure cultures of 



anaerobes by means of it", p. 1219. 

 J. BOEKE and J. Q. DUSSER DE BarennE: "The sympathetic innervation of the cross-striated muscle 



fibres of vertebrates'', p. 1227. (With one plate). 

 Erik AODUHR: „Are the cross-striated muscle fibres of the extremities also innervated sympathe- 

 tically?" (Communicated by Prof. J. BOEKE , p. 1231. 

 J. G. DusSER DE Barenne: 'Once more the innervation and the tonus of the striped muscles'". 



(Communicated by Prof. J. BOEKE), p. 1238. 

 M. j. HuiZiNOA: "The Unidirectional Resistance of Crystal Detectors'. (Communicated by Prof. 



H. HAQA), p. 1248. (With one plate). 

 Errata, p. 1258. 



73 



Proceedings Royal Acad. Amsterdam. Vol. XXI. 



