ON SOME APPLICATIONS OF ELECTRIC ENERGY. 477 



opinioB, tliafc the yellow ray and not the violet ray was most efficacious in 

 promoting the decomposition of carbonic acid in the vegetable cell. 



Having, in consequence of these preliminary inquiries, determined to 

 surround the electric arc with a clear glass lantern, more satisfactory 

 results were soon observable. Thus, peas which had been sown at the 

 end of October, produced a harvest of ripe fruit on February 16, 

 under the influence, with the exception of Sunday nights, of continuous 

 light. Raspberry stalks, put into the house on December 16th, pro- 

 duced ripe fruit on the 1st of March, and strawberry plants, put in about 

 the same time, produced T'ipe fruit of excellent flavour and colour on Feb- 

 ruary 14. Vines which broke on December 26, produced ripe gi'apes of 

 stronger flavour than usual on March 10. Wheat, barley, and oats shot 

 up with extraordinary rapidity under the influence of continuous light, 

 but did not arrive at maturity ; their growth having been too rapid for 

 their strength, caused them to fall to the ground, after having attained 

 the height of about twelve inches. 



Seeds of wheat, barley, and oats planted in the open air, and grown 

 under the influence of the external electric light, produced, however, more 

 satisfactory results ; having been sown in rows on January 6, they ger- 

 minated with difficulty on account of frost and snow on the ground, but 

 developed rapidly when milder weather set in, and showed ripe grain by 

 the end of June, having been aided in their growth by the electi-ic light 

 until the beginning of May. 



Doubts have been expressed by some botanists whether plants grown 

 and brought to matui'ity under the influence of continuous light would 

 produce fruit capable of reproduction, and in order to test this question, 

 the peas gathered on February 16 from the plants which had been grown 

 under almost continuous light-action, were replanted on February 18. 

 They vegetated in a few days, showing every appearance of healthy 

 gi'owth. 



Further evidence on the same question will be obtained by Dr. 

 Gilbert, F.R.S., who has undertaken to experiment upon the wheat, 

 barley, and oats grown as above stated ; but still more evidence will 

 pi'obably be required before all doubt on the subject can be allayed. 



I am aware that the great weight of the opinion of Dr. Darwin goes 

 in favour of the view that many plants, if not all of them, require diurnal 

 rest for their normal development. In his great work on ' The Movements 

 of Plants ' he deals in reality with plant life as it exists under the 

 alternating influence of solar light and darkness ; he investigates with 

 astonishing precision and minuteness their natural movements of circum- 

 nutation and nightly or nyctitropic action, but does not extend his 

 inquiries to the conditions resulting from continuoiTS light. He clearly 

 proves that nyctitropic action is instituted to protect the delicate leaf-cells 

 of plants from refrigeration by radiation into space, but it does not follow, 

 I would submit, that this protecting power involves the necessity of the 

 hurtful influence. May it not rather be inferred from Dr. Darwin's 

 investigations that the absence of light during night-time involved a 

 difficulty to plant life that had to be met by special motor organs, which 

 latter would perhaps be gradually dispensed with by plants if exposed to 

 continual light for some years or generations ? 



It is with great diffidence, and without wishing to generalise, that I 

 feel bound to state, as the result of all my experiments, extending now over 

 two winters, that although periodic darkness evidently favours growth in 



