238 



[Numerous auxanomctpr icadjiiys w.i.- m i.l. upon rfpiesentativo plants tluring 

 1890-91. A record of the growth of two petunia plants, alike mall resp»"rts, isgrjv«»n."l 



The average growth per hour is as follows : 



With electric light, 8 to 11 p. m., 0.0416 inches; 11 p. m. to 8 a. m., U.0243 inches: 

 8 a. m. to 8 p. m., 0.0312 inches. Without electric light, 8 to 11 p. m., 0.0234 inches : 

 11 p. ni. to 8 a. ni., 0.022;"i inches; 8 a. m. to 8 p. m., 0.0234 inches. 



The greatest growth took place when the electric light was burning. 



In all these experiments with ornamental plants it was noticeable that the light 

 exercised a very injurious etie* t witliin a ratlins of about 6 feet. Between 6 and 8 

 feet the results were indirtVreut, ami l>c.vond that point there was usually a notice- 

 able tendency towards a taller and straighter growth, and it seemed to us that at 

 distances of a dozen feet or more the flowers were more intense in color, particularly 

 when they first opened, There was usually a perceptiVde gain in earliness in the 

 light house also. On the whole, I feel that it will be possible some day to use the 

 electric light in floricultural establishments to some pecuniary advantage. 



Uxperimen ts else it h ere. 



The first experiment to determine the influence of electric light upon vegetation 

 was made by Herv«5-Mangou in IWJl." This experinu-nt showeil that the electri' 

 light can cause the production of dilorophyll or the green color in plants, and als^' 

 that the light can produce heliotropism, or the phenomenon of turning or bendiiiu 

 towards the light. 



In 18t)9 Prillieuxt showed that the electric light, in common with other arlilicial 

 lights, is capalde of pminoting assimilation, or the deiomjiosition of rarlmn didxidr 

 and water. 



[The only otlier ini|)i)rtant investigations of the subject from ahorti< iiltiiral staml- 

 point appear to hav*- been those of C. W. Siemens in Kngland, and P. P. Deherain in 

 France.] Dr. .Siemens's experiments* may be divided into two series; in one series 

 the lamp was placed inside tlie greenhouse and in the other suspended over it. 



[In his first experiment a lamp of 1,400 candle power was used. Tlie foliage of 

 melon and cucumber })lan1s jdaced within 3 or 4 feet of this lamp was much 

 injured. When the ]dants were removed to a distance of 7 or 8 feet they showed sign- 

 of recovery ami made new leaves.] In gent-ral all plants which were exposed t<> 

 normal <onditi<>ns <lnring tin? day and to 6 hours of electric light at night '' far sui 

 passed the others in darkness of green and vigorous appearance generally." Tlie 

 flavor was fully as good in the electric-light fruits as in the otlu-i-s. These results 

 were supplemented by a larger experiment in the winter of 1880-81. In this case 

 a lamp of 4,000 candle power was used, and it was i>laced inside a house of 2,318 

 cubic feet cai)acity. The light was run all night and the arc was at first not pro- 

 tected by a globe. The ''results were anything but satisfactory," the plants soon 

 becoming withered. At this point a globe of clear glass was placed upon the lam)>. 

 and therealter the most satisfactory n-sults were obtained. Peas, rasplterries, straw- 

 berries. gra])es. melons, and bananas frrited e.arly and abundantly under continuous 

 light — solar light by day and electric light by night. The strawberries are said to 

 have been "of excellent flavor and color," and the grapes of "stronger flavor than 

 tjsual."' The banan.is were " prcmoiinced by competent judges unsurpassed in flavor." 

 and the melons were " remarkable for size and aromatic flavor." Wheat, barley, and 

 oats grew so rapidly that they fell to the giound from their own weiglit. The ben- 

 eticial influence of the clear glass globe was therefore most marked. * * » 



In the other series of experiments Siemens placed an electric lara]» of 1.400 eaiidl. 

 power about 7 feet above a sunken melon pit which was covered with glass. Tin 



*Corapt. rend.. 53. 243. 

 tCompt. rend., 69, 410. 



IProc. Roy. .Soc. 30. 210, 293. Kep. British A. A. S.. 1881. 474. See .also .abstract 

 in Nature. 21. 4.56 (Mar. 11. 1880), ami an editminl iu the same issue. 



