S'6(o, Hi^ 



CONTENTS. 



VOL. XIII. 



No. PAGE 



I. — A Seed-Bearing Irish Pteridosperm, Crob^Aheca Honinghausi, 

 Kidston {Lyginoclendron oldhamium, Williamson). By 

 T. Johnson, d.sc, f.l.s. (Plates I.-III.) (March 8, 1911.) . 1 



n. — Considerations and Experiments on the supposed Infection of 

 the Potato Crop with the Blight Fungus {Phytophthora 

 infestans) by means of Mycelium derived directly from the 

 planted Tubers. By Geokge H. PETHYBEmGE, b.sc, ph.d. 

 (March 6, 1911.) ...... 12 



III. — Mechanical Stress and Magnetisation of Nickel (Part II.), and 

 the Subsidence of Torsional Oscillations in Nickel and Iron 

 Wires when subjected to the Influence of Longitudinal Magnetic 

 Fields. By William Beown, b.sc. (April 15, 1911.) . . 28 



IV. — A Thermo-Electrie Method of Cryoscopy. By Heney H. Dixon, 



so.D., F.E.s. (April 20, 1911.) . . . .49 



V. — A Method of Exact Determination of the Continuous Change in 

 Absolute Density of a Substance, e.g. Wax, in passing through 

 its Fusion Stage. By William J. Lyons, b.a., a.e.c.so. (lond.). 

 (May 16, 1911.) ...... 63 



VI. — Eadiant Matter. By John Joly, sc.d., f.k.s. (June 9, 1911.) . 73 

 VII. — The Inheritance of Milk- Yield in Cattle. By James Wilson, m.a., 



b.sc. (June 12, 1911.) . . . . .89 



VIII. — Is Archffiopteris a Pteridosperm ? By T. Johnson, d.sc, f.l.s. 



(Plates IV.-VI.) (June 28, 1911.) 114 



IX. — The Occurrence of Archceopteris Tscherinahi, Stur, and of other 

 Species of Archfeopteris in Ireland. By T. Johnson, d.sc, 

 F.L.S. (Plates VII. and VIII.) (June 28, 1911.) . . 137 



X. — Award of the Boyle Medal to Pkofessoe John Joly, m.a., so.d,, 



F.E.s. (July, 1911.) . . . . . .142 



XI. — On the Amount of Kadium Emanation in the Soil and its Escape 

 into the Atmosphere. By John Joly, sc.d., f.e.s., and Louis B. 

 Smyth, b.a. (Plate IX.) (August 29, 1911.) . . 148 



XII. — Contributions to our Knowledge of the Floras of the Irish 

 Carboniferous Eocks. Part I. By E. A. Newell Aebek, m.a., 

 F.L.S., F.G.s. (Plates X.-XII.) (January 20, 1912.) . 162 



