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CONTENTS 
OF VOL. 173. 
PAET I. 
T. On the Electromotive Properties of the Leaf of Dioncea in the Excited and Unexcited 
States. By J. Burdon-Sanderson, M. D ., E.P.S., Professor of Physiology in 
University College, London .. page 1 
II. Lucifer: a Study in Morphology. By W. K. Brooks, Associate in Biology and 
Director of the Chesapeake Zoological Laboratory of the Johns Hopkins 
University , Baltimore, Md., U.S.A. Communicated by Professor Huxley, 
Sec. P.S .. 57 
III. On the Structure and Development of the Skidl in Sturgeons (Acipenser ruthenus 
and A. sturio). By William Kitchen Parker, F.R.S. . 139 
IV. On the Stresses caused in the Interior of the Earth by the Weight of Continents 
and Mountains. By G. H. Darwin, F.R.S. .187 
Y. Experimental Determination of the Velocity of White and of Coloured Light. By 
James Young, LL.D., F.R.S ., and Professor G. Forbes.231 
YI. The Bakerian Lecture. — Action of Free Molecides on Radiant Heat, and its 
Conversion thereby into Sound. By John Tyndall, F.R.S. .291 
Index to Part I. . . qk- 
PART II. 
YII. On the Structure and Development of Lepidosteus. By F. M. Balfour, LL.D., 
F.R.S., Fellow of Trinity College, Cambridge, and W. 1ST. Parker, Assistant 
in die Biological Laboratory of the Normal School of Science, South 
Kensington . ok () 
