Royal Society. 151 



diflFerent degrees ; and if the gas be wholly or mainly hydrogen, 

 reduction takes place whether the plate be positive or negative. 



At certain intermediate states of mixture rings or zones of alter- 

 nate oxidation and reduction are shown, quite distinguishable from 

 the ordinary succession of colours of thin plates, and showing 

 alternations or periods of interference of electrical action. 



The author then gives the results of experiments with several 

 other metals, of which bismuth was the only one he found to produce 

 effects anything like equal to the silver, though other metals showed 

 them in some degree. 



He also varied the gas or gases employed, and details the results 

 obtained with several gases ; among them carbonic oxide is the 

 most worthy of note, as with it effects are produced similar to those 

 with the mixture of oxygen and h5^drogen, viz. oxidation when the 

 plate was positive, and reduction when it was negative. 



The author's theory or mode of explaining the results is as follows. 

 The discharges are successive, not continuous, and antecedent to 

 each discharge the intervening gas is thrown into a state of chemical 

 polarity, similar to that which takes place in an electrolyte anterior 

 to electrolysis ; by this means the positive terminal has in juxta- 

 position with it oxygen or an electro-negative gas ; the discharge 

 takes place, and by the superficial ignition the layer of oxygen com- 

 oines with the metal in contact with it. 



Conversely, when the oxidated surface is negative and in contact 

 with an electro-positive gas, the heat of the discharge produces re- 

 duction. The fact of oxidation only taking place when air or oxygen 

 alone are present, and reduction only when hydrogen is present, he 

 considers irreconcilable with the effects being attributable to the dis- 

 charge itself, or to their being regarded as analogous to electrolysis ; 

 while these phenomena are corroborative of the view he puts forth. 



The author refers to the experiments of Priestley, Karsten and 

 others, in which spots or marks have been shown to be produced by 

 electrical discharge, but which do not otherwise bear upon the ob- 

 jects sought to be elucidated by this paper. 



April 22. — The following papers were read : — 



1. " On the Structure of the Stem of Victoria regia." By Arthur 

 Henfrey, F.L.S. &c. Communicated by Professor Edward Forbes, 

 F.R.S. 



The investigation of the anatomy of Victoria regia acquires its 

 interest from the fact of the relations which have been pointed out 

 to exist between the Nymphajacese and some of the undoubted 

 Monocotyledonous families, especially also from the researches of 

 M. Trecul on the anatomy of Nuphar lutea, which plant that author 

 describes as having a stem of th-e Monocotyledonous type of struc- 

 ture. Through the unfortunate death of the plant of Victoria regia, 

 which had flowered for some time in the gardens of the Koyal 

 Botanic Society of London, the author had an opportunity of ex- 

 amining the anatomy of its stem. It is an upright rhizome, with 

 undeveloped internodes, growing by a single terminal bud, appa- 

 rently perennially, and attaining considerable thickness ; on the out- 

 side it bears the remains of the petioles and flower-stalks, which 



