Contents. v 



Xo. PAGE 



XXIII. — A New Principle in Blowpipe Construction. By H, G. Becker, 



A.K.c.sG.i., A.i.G. (August, 1921.) .... 275 



XXIV. — Uncharged Nuclei produced in Moist Air by Ultra-Violet Light 

 and other Sources. By the late Prof. J. A. McClelland, 

 F.K.S., and J. J. M'Heney, m.so. (August, 1921.) . . 282 



XXV. — Biological Studies of Aphis rumicis L. A. — Appearance of 

 Winged Forms. B. — Appearance of Sexual Forms. By 

 J. Davidson, d.sc. (August, 1921.) .... 304 



XXVI. — The Occurrence of Dewalquea in the Coal-Bore at Washing 

 Bay. By T. Johnson, d.sc, f.l.s., and .Iane G. Gilmoee, 

 B.so. (Plates XI, XII.) (August, 1921.) . . .325 



XXVII. — A Simple Form of Apparatus for observing the Eate of Eeaction 

 between Gases and Liquids, and its use in determining the 

 Eate of Solution of Oxygen by Water under different con- 

 ditions of Mixing. By H. G. Beckee, a.e.c.so.i., a. i.e. 

 (August, 1921.) . . . . . .334 



XXVIII. — The Occurrence of a Sequoia at Washing Bay. By T. Johnson, 

 D.sc, F.L.S., and Jane G. Gilmoee, b.so. (Plates XIII, XIV.) 

 (August, 1921.) . . . . . .345 



XXIX. — The Sources of Infection of Potato Tubers with the Blight 

 Fungus, PhytophtJwra infestans. By Paul A. Muhphy, b.a., 

 A.E.o.sci. (August, 1921.) . . . . .353 



XXX. — Some Factors affecting the Hydrogen Ion Concentration of 

 the Soil and its Eelation to Plant Distribution. By W. E. 

 G. Atkins, o.b.e., sc.d., f.i.c. (February, 1922.) . . 369 



XXXI.— The Hydrogen Ion Concentration of Plant Cells. By W. E. G. 



Atkins, o.b.e., sc.d., f.i.c (February, 1922.) . . 414 



XXXII. — Note on the Occurrence of the Finger and Toe Disease of 

 Turnips in Eelation to the Hydrogen Ion Concentration of 

 the Soil. By W. R. G. Atkins, o.b.e., SC.D., f.i.c (February, 

 1922.) . . . . . . .427 



XXXIII. — Photosynthesis and the Electronic Theory (II). By Henry 

 H. Dixon, sc.d., f.e.s., and Nigel G. Ball, m.a. (February, 

 1922.) . . . • . . .435 



XXXIV. — The Bionomics of the Conidia of Phytophthora infestans (Mont.) 

 De Bary. By Paul A. Muephy, b.a., a.r.csci. (February, 

 1922.) . . . . . . .442 



XXXV. — On the Distribution of Activity in Eadium Therapy under 

 different conditions of Screening. By H. H. Poole, m.a., 

 so.D. (April, 1922.) . . . . .467 



