KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 



TE AMSTERDAM. 



PROCEEDINGS 



VOLUME XXV 

 NOS. \ and 2. 



President: Prof. F. A. F. C. Went. 

 Secretary : Prof. L. BOLK. 



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

 Natuurkundige Afdeeling." Vol. XXXI). 



CONTENTS. 



P. Ehrenfest and G. Breit: "A remarkable case of quantization", p. 2. 



G. L. FUNKE: "The influence of hydrogen ion concentration upon the action of the amylase of 



Aspergillus niger". (Communicated by Prof. F. A. F. C. WENT), p. 6. 

 R. KRaliSEL: „Ueber einen fossilen Baumstamm von Bolang (Java), ein Beitrag zur Kenntnis der 

 fossilen Flora Niederlandisch-Indiens". (Communicated by Prof. J. W. Moll), p. 9. (Mit 1 Tafel). 

 L. BOLK: "On the Significance of the Supra-orbital Ridges in the Primates", p. 16. 

 Jan De Vries: "Representation of a Bilinear Congruence of Twisted Cubics on a Bilinear Con- 

 gruence of Rays", p. 22. 

 J. M. Bijvoet and A. Karssen: "Research by means of Röntgen-Rays on the Structure of the 



Crystals of Lithium and some of jts Compounds with Light Elements. II. Lithium-Hydride". 



(Communicated by Prof. P. Zeeman), p. 27. 

 |. W. JANZEN and L. K. WOLFF: "Studies about d'Herelle's Bact«riophagus". (Communicated by 



Prof. C. Eykman), p. 31. 

 K. LandsteineR: "Experiments on Anaphylaxis with Azoproteins". (Communicated by Prof. C. H. H. 



SPRONCK), p. 34. 

 K. J. Ferinoa: "On the Causes of the Emigration of Leukocytes". (Communicated by Prof. H. J. 



HAMBURGER), p. 36. 



Robert F. Griggs : "Observations on the Incandescent Sand Flow of the Valley of ten thousand 



smokes", p. 42. 

 Erratum, p. 50. 



Proceedings Royal Acad. Amsterdam. Vol. XXV. 



