6io SCIENCE PROGRESS 



And the early method of investigation may not have been so 

 wasteful after all, for we know how, to-day, fresh fields of 

 investigation are opened out by new combinations of subjects. 



In reviewing, then, the course of investigations in the time 

 of Priestley, we find that the subject of electroculture was as 

 favourite a one for examination as other branches of electrical 

 science. We cannot avoid asking ourselves, therefore, how 

 it is that while the study of electricity and its many industrial 

 applications has developed into enormous importance, electro- 

 culture in the meantime has remained practically stationary 

 for a century and a half, and this in spite of its obvious economic 

 importance. 



We probably find the answer to this question in the stag- 

 nation of the science of the living plant. The development of 

 electroculture depends not only on the development of our 

 knowledge of pure physics, but also on the development of our 

 knowledge of the activities of the plant. While physics has 

 developed so rapidly, the science of the living plant remains 

 very much where it was when Woodward and Stephen Hales 

 performed their experiments. While some excuse for this 

 may be found in the political and economic conditions which 

 have determined the position of agriculture, the main reason 

 for this state of affairs must be that the science of the living 

 plant has not attracted the genius which has been bestowed 

 on electrical science for instance. 



For the sake of simplicity we shall only deal in this article 

 with the form of electroculture in which electricity is dis- 

 charged through the air to the plants from an overhead wire 

 system, kept charged at a high potential by an electrical machine, 

 or simply charged by atmospheric electricity collected at a 

 higher altitude. This is the only form of apparatus for electro- 

 culture which has been employed on anything like a commercial 

 scale, although very numerous experiments have been also 

 made by passing currents through the soil in which the experi- 

 mental plants are growing. 



The subject, even with the restriction which we have 

 indicated in the last paragraph, has such an enormous litera- 

 ture that we shall only attempt to cite the work of a few 

 investigators typical of the various periods in which they made 

 their observations. From these typical investigations we shall 

 see how it appears to be manifest that electricity in certain 



