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Contents. 



January 26, 1891. page 



On the Electric Discharge through rarefied gases without electrodes. 



By Professor J. J. Thomson . 131 



On the Laws of the Diffraction at Caustic Surfaces. By J. Larmor . 131 

 On the effect of Temperature on the Conductivity of Solutions of 



Sulphuric Acid. By Miss H. G. Klaassen . . . . .137 



February 9, 1891. 



On Rectipetality and on a modification of the Klinostat. By Miss 



Dorothea F. M. Pertz and Mr Francis Darwin . . . .141 



On the Occurrence of Bipalium Ketvense, Moseley, in a new Locality; 



with a Note upon the Urticating Organs. By A. E. Shipley . .142 



On the Medusae of Millepora and their relations to the medusiform 



gonophores of the ffydroniedusce. By S. J. Hickson . . .147 



On the Development of the Oviduct in the Frog. By E. W. MacBride . 148 



February 23, 1891. 



On Tidal Prediction — a general account of the theory and methods in 



use and the accuracy attained. By Professor G. H. Darwin . .151 



On Quaternion Functions, with especial Reference to the Discussion 



of Laplace's Equation. By J. Brill 151 



March 9, 1891. 



On the disturbances of the body temperature of the fowl which follow 



total extirpation of the fore-brain. By J. George Adami . .156 



On the nature of Supernumerary Appendages in Insects. By W. 



Bateson 159 



On the Orientation of Sacculina. By Theo. T. Groom . . . .160 



On some experiments on blood-clotting. By Albert S. Griinbaum . .163 



May 4, 1891. 



On the most general type of electrical waves in dielectric media that is 



consistent with ascertained laws. By J. Larmor . . . .164 



On a mechanical representation of a vibrating electrical system, and its 



radiation. By J. Larmor 165 



On the Theory of Discontinuous Fluid Motions in two dimensions. 



By A. E. H. Love . . .175 



On thin rotating isotropic disks. By C. Chree 201 



