240 THE SCIENTIFIC PAPERS OF 



tinuous light, and I might almost suggest the idea that the 

 formation of sugar is the very last action that goes on in fruit ; 

 after the fruit has formed, developed, and acquired its aromatic 

 qualities, then the formation of sugar seems to step in, as though 

 it were the first stage of decay. Several botanists of high standing 

 (Professor Cohen, of Leipzig, and others) have expressed the 

 opinion that the growth of plants takes place chiefly at night : 

 and there seems to be no doubt that during the night delicate and 

 quick-growing plants, such as cucumbers and melons, make very 

 considerable progress. But in that case they remain thin and 

 yellow, whereas with continuous light they make less progress in 

 length, but develop more in colour, in breadth, and in vigour ; 

 so that the truth may lie between the two views that, for most 

 rapid growth, intermittent light and darkness may be necessary, 

 but that for vigorous development, and for the formation of fruit, 

 it is not desirable. 



The experiments now in preparation will perhaps settle some of 

 these points, and will further show what can be done in this 

 direction from a practical point of view. 



Is it possible to make use of electric aid for growing plants 

 and developing fruit that could be brought to the market ? This 

 is a mixed question. It depends, in the first place, upon the 

 amount of effect that can be produced, and, in the second place, 

 upon the cost. My opinion is, that the result of experiments on 

 a large scale will come out favourably as regards its application 

 to high-class horticulture. By working a steam engine, and using 

 the waste steam to heat the water that circulates through the 

 stoves, I believe that there will be very little extra consumption of 

 fuel ; and if that view be realised, the expense of the electric light 

 will not be great at all, and the steam engine could be used in the 

 daytime for various other ordinary useful purposes. 



Then with regard to the spectrum experiments. It is an open 

 question which portion of solar light is really efficacious in forming 

 chlorophyll, and which in promoting growth and in producing 

 starch and fibrous matter. The difficulty in experimenting with 

 solar light is obvious. Since the days of Joshua the sun has not 

 been standing still, and the power of making it do so is beyond 

 the skill of botanists, hence the difficulty of obtaining a standing 

 spectrum by which to notice sensible effects produced from any 



