40 M. Martins on the Vegetable Colonisation of the 



nominated electrogenic. It might be viewed as one of po- 

 larization ; its discharge one of depolarization. But I have 

 nothing to add to these views, beyond what is universally 

 known. The phenomena of the continuous, interrupted, and 

 sudden discharge of the electrogenic condition, have not, I 

 believe, been traced and detailed before. 



On the Vegetable Colonisation of the British Islands, Shetland, 

 Feroe, and Iceland. By M. Ch. Martins. 



Whether each plant has originated in the place where it 

 is now found, or whether there be centres of creation, from 

 which vegetables have been diffused by radiating over the 

 surface of the earth, are the two systems which have long 

 divided natural philosophers. Some of them, avoiding in 

 some degree the discussion of the problem, suppose that the 

 plant was produced in the locality where we now observe it 

 vegetating ; others, on the contrary, admit of great vegetable 

 migrations similar to those of the human races. Applying 

 to these questions the notions which geology furnishes re- 

 specting the past state of the globe, and such as are afforded 

 by the physical history and meteorology of its present condi- 

 tion, they are not satisfied by regarding the geographical 

 distribution of species as a fact without premises and without 

 consequences. They endeavour to recognise in it the traces 

 of the last revolutions of our planet, and the action of the 

 numerous and varied forces which impede or favour the dis- 

 semination of vegetables in the present day. They attempt to 

 trace on the map the progress of these vegetable armies 

 which have invaded certain countries, while others have pre- 

 served their primitive flora. These studies are but of yester- 

 day's date ; but by submitting them to reflecting minds, we 

 hope to make their importance felt. In fact, the creation of 

 existing vegetables followed very closely upon the emergence 

 of continents and islands. It is in some degree the last act 

 in the geological history of our globe. Man appeared at a 

 later period, and tradition commenced. 



