CONTENTS XIX 



Verschoyle (T.), a. Th. van Urk and J. P. Kuenen. Isotherms of 

 di-atomic substances and their binary mixtures. XX. The critical curve 

 of oxygen-nitrogen mixtures, the critical phenomena and some isotherms 

 of two mixtures with 50 "/q and 75 "/q by volume of oxygen in the 

 neighbourhood of the critical point. 49. 



Visser (S. W.). A non-tangent infralateral arc. 712. 



Vogelkop v. Bird's head. 



volta-luminescence. 561. 



Vries (Jan de). A null system (I, 2, 3). 124. 



— A congruence (1,0) of twisted cubics. 126. 



— A representation of the line elements of a plane on the tangents of 

 a hyperboloid. 129. 



— Representation of a tetrahedral complex on the points of space. 390. 

 Vries (O. de). The coagulation of Hevea latex. 675. 



Waerden (B. L. van der). Ueber das Komitantensystem zweier und 



dreier ternarer quadratischer Formen. 2. 

 Water (On the bacteriophage and the self-purification of). 116. 



— (Researches on the addition of) to ethylene and propylene. 321. 



— (The binding of) by animal carbon. 548. 



Waterman (H. I.) and J. N. J. Perquin. Hydrogenation of paraffin by 



the Bergius' method. 226. 

 Weevers (Th.). Ringing experiments with variegated branches. 756. 

 Weitzenböck (R.). Ueber Invarianten von Bilinearformen. 801. 

 Wibaut (J. P.) and J. J. Diekmann. Researches on the addition of water 



to ethylene and propylene. (Preliminary communication). 321. 



— and Miss Elisabeth Dingemanse. The synthesis of some pyridyl- 

 pyrroles. 426. 



Wiersma (Miss Heleeni and F. F. Hazelhoff. On subjective rhythm- 



isation. 462. 

 Winkler (C). A partial foetus removed from a child. 493. 

 W I nk LE R-J u N I u s (E.) and J. A. Latumeten. The histopathology of Lyssa 



in respect to the propagation of the lyssavirus. 825. 

 WoERDEMAN (M. W.). On the determination of polarity in tiie epidermal 



ciliated cell. (After experiments on amphibian larvae). 702. 



— A contribution to the histophysiology of the ciliated epithelium. 707. 

 Wolff (J.). On the points of continuity of functions. 187. 



— Inner limiting sets. 189. 



Wolff (L. K.) and G. M. Kraay. The splitting of lipoids by bacteria. 1. 436. 



Woltjer (H. R.). Magnetic researches. XXII. On the determination of the 

 magnetisation at very low temperatures and on the susceptibility of 

 gadolinium sulphate in the region of temperatures obtainable with 

 liquid hydrogen. 613. 



