jIV CONTENTS 



ONNEs (H. kameelingh) and VV. H. Keesom. The specific heat at low tempera- 

 tures. IV. Measurements of the specific heat of fusion of hydrogen. 1000. 



OPACIÜE pabticles (On the diöractiou phenomenon caused by a great number of 

 irregularly distributed apertures or). 1278. 



ORGANO-MAGNESIUM Compounds (Action of) on, and reduction of cineol. 66. 



OBN STEIN (l. s.) and W. J. H. Moll. Contribution to the research of liquid 

 crystals XL. The influence of the temperature on the extinction ; further experiments 

 upon the influence of the magnetic field. 210. 



OSCILLATION (Semi-diurnal horizontal) of the free atmosphere up to 10 km above 

 sea level deduced from pilotballoon observations at Batavia. 119. 



PANNEKOEK (a.). The Origin of the Saros. 943. 



PABALLAX (Ou the) of some stellar clusters. 1st Comm. 1108. 



Pasteur's principle (Investigations into) of the connection between molecular and 

 crystallonomical dissymmetry HI. Racemic and optically active complex salts of 

 trivalent rhodium, 244. IV. Racemic and optically active complex salts of 

 Ehodium-tri-oxalic-acid. 263. 



PEKELHAEING (c. A.) presents a paper of Miss. A. van Herwebden: "On the 

 nature and the significance of voluntin in yeast-cells. 70. 



presents a paper of Dr. J. W. Le Heux: '-On the nature of the constituent of 



Intestine-extracts, which exerts a stimulating influence upon the gastro-inteatinal 

 movements". 805. 



— presents a paper of Dr. P. Niedwenudyse : "A contribution to the pathological 

 histology of striated muscle. -tissue". 883. 



— presents a paper of Mr. H. van Trigt: "A contribution to the physiology of 

 the fresh-water sponges (Spongillidae)". 1U61. 



periodic system (On the fundamental values of the quantites b and 1/ a for different 



elements, in connection with the). V. 492. VI. 505. 

 peristalsis (On the efl'ect of H3O2 on the) of the isolated intestine. 861. 

 PERMEABILITY (Experimental reseaches on the) of the kidneys to glucose. 668. 

 phosphorus (On the critical temperature and pressure of mercury and). 138. 



— (On black). II. 392. 



photography of the fundus of the human eye. 326. 



— (On a method of determining spectral intensities by means of). 1021. 

 Physics. H. A. Lorentz: "On Einstein's theory of gravitation". Part. III. 2. IV. 20. 



— Th. de Donder: "Sur les equations différentielles du champ gravifique". 97. 



— J. J. VAN Laar: "On the critical temperature and pressure of Mercury and 

 Phosphorus". 138. 



— J. M. Burgers: "Adiabatic invariants of mechanical systems". I. 149. II. 158. 

 III. 163. 



— J. M. Burgers: "The spectrum of a rotating molecule according to the theory 

 of quanta". 170. 



— H. Kamerlingh Onnes, C. A. Crommelin and P. G. Cath: "Isothermals of 

 di-atomic substances and their binary mixtures". XIX. 178. 



