1873.] On the Action of Electricity on Gases. 483 



cases as those just named seem to show that a weak constructive energy 

 has a great tendency to give rise to results analogous to those due to one 

 of low type. If this conclusion should be confirmed by further research, 

 it would be an important fact in connexion with the theory of evolution, 

 since it would show that, as in the organization of animals, where deve- 

 lopment is arrested, there is a more or less permanent continuance of a 

 lower type of structure, so in plants there is a permanent continuance of 

 a lower type of colouring. 



Conclusion. 



Such, then, is a general account of the present state of what I have 

 named comparative vegetable chromatology. I cannot but feel that it is 

 very incomplete, both in compass and in detail, and that much remains 

 to be learned respecting nearly every thing connected with it. Not only 

 are the natural objects requiring careful study very numerous and often 

 difficult to obtain in a proper condition, but, as will have been seen, 

 several new questions are most intimately connected with my subject — ■ 

 questions of great interest in connexion with optics and chemistry, which 

 would probably never have been raised if it had not been for their rela- 

 tion to the facts I have described. There are indications of other general 

 questions which have not yet been fairly examined, and, in fact, the whole 

 subject must be looked upon as being quite in its infancy. At the same 

 time I trust that what I have described will be sufficient to show that 

 the nature and relative proportion of the various colouring-matters in 

 plants must have some very important signification, and that a more com- 

 plete knowledge of comparative vegetable chromatology may be expected 

 to throw much light on the development of plants, and enable us to 

 examine some of the most fundamental questions in biology from a new 

 and independent point of view. The subject is also interesting in other 

 respects. The storing up of the energy of the sun's rays in the various 

 compounds formed by plants is probably so intimately connected with 

 the optical and chemical properties of some of their coloured constituents, 

 that the further extension of such inquiries as I have described may 

 possibly assist in clearing up this very difficult and yet most important 

 problem. 



XXIII. " On the Action of Electricity on Gases.— No. II. On 

 the Electric Decomposition of Carbonic- Acid Gas." By Sir 

 B. C. Brodie, Bart., D.C.L., F.R.S., late Waynflete Pro- 

 fessor of Chemistry in the University of Oxford. Received 

 June 19, 1873. 



(Abstract.) 



In my previous experiments the maximum amount of ozone obtained 

 by the action of electricity upon pure oxygen passed through the induc- 

 tion-tube of W. Siemens was about 20 per cent., an amount which, under 



