496 British Association for the Advancement of Science. 



The Rev. Dr. Drummond stated that, from observations lately 

 made by him, the Gordius aquaticus seems to be viviparous. 



On the Action of Light on Plants. By Professor Daubeny. 



Professor Daubeny reported the progress which he has made in 

 his experiments on this subject since 1833, when he communicated 

 the results obtained up to that time to the British Association at 

 Cambridge. At that period he had ascertained that the quantity of 

 carbonic acid decomposed by a plant was in proportion, not to the 

 chemical or heating influence of the ray transmitted to it, but to its 

 illuminating power : he has since found that the functions of ex- 

 haling moisture by the leaves, and absorbing it by the roots, depend 

 upon the same law ; with this difference, however, that, provided 

 some light be present, a body radiating much heat will serve as a 

 substitute for one transmitting a greater degree of light. Thus, a 

 solution of ammonio-sulphate of copper, which absorbs and conse- 

 quently radiates much heat, is nearly as efficient in causing the ex- 

 halation and absorption of moisture as glass, which transmits the 

 entire spectrum ; and in proof that this does not depend upon any 

 peculiar power residing in the violet ray, water obscured by ink, so 

 as to produce an equally feeble illuminating effect, was found, in 

 consequence of the heat it radiated, to produce an equal degree of 

 exhalation. Yet when the plant was covered over by opake bodies 

 radiating much heat, the amount of moisture exhaled was very in- 

 considerable. 



Professor Daubeny has employed, in his experiments on plants, 

 the light emitted by balls of lime ignited by the oxy-hydrogen jet, 

 but could not discover that it exerted any influence on the quantity 

 of moisture exhaled by them. 



Observations on the Structure of Horizontal Branches of Coniferae. 

 By William Nicol. 



In a paper on the structure of recent and fossil Gtonifera, inserted 

 in Professor Jameson's Philosophical Journal for January 1834, the 

 author gave an account of a very striking difference he had observed 

 in the structure of the opposite sides of a piece of the wood of Taxo- 

 dium disticha. The pith was much nearer one side than the other, 

 and the narrowest was of a paler colour than the broadest side. The 

 narrow side showed the usual structure of the true Pines in all the 

 three principal sections, but the broad side in the transverse sec- 

 tion possessed a greater degree of solidity than the narrowest side, 

 and in both the longitudinal sections the vessels were filled with de- 

 cussating fibres, and the discs were not only more sparingly bestowed 

 but were also smaller and more obscure than those occurring in the 

 other side. At the time this wood was examined he did not know 

 whether it was a portion of a stem or a branch. He has since as- 

 certained that it was a horizontal branch, and it then became inter- 

 esting to determine whether the difference of structures was peculiar 



