ELECTRICITY AND PLANT-GROWING. 61 



and size of leaves with increased distance from the lamp. Those 

 nearest the lamp made most leaves early in their growth, and they 

 maintained this advantage until about four weeks old, although 

 the leaves were smaller. Five weeks after sowing, the average 

 height of plants within four feet of the lamp was 1.2 inches; 

 between four and five feet, 1.34 inches; between five and six 

 feet 1.8 inches ; between six and seven feet, 2 inches; between 

 seven and eight feet, 2.2 inches. The average height of plants in 

 the dark house at this time was 2^ inches, and the plants were 

 much more vigorous, and had larger and darker leaves. The 

 increase in size was not uniform with increase in distance from the 

 lamp. There were somewhat regular alternations of lower and 

 higher plants, although there was a general progression in height. 

 This alternating elevation and depression was probably due to the 

 concentric bands of varying intensity of light which fall from the 

 arc, and which are caused by the uneven burning of the carbons, 

 those zones which were marked by the shadow giving the better 

 results in growth. Cress and endive gave similar results. With 

 endive we chanced to get a signal illustration of the injurious 

 effect of the light. One of two parallel rows of plants was in the 

 shade of a post, and while the exposed row gradually increased in 

 size as it proceeded from the light, this shaded row gradually 

 decreased, or was largest nearest the light where the shadow was 

 most intense. 



Some of the most marked results in this first series of experi- 

 ments were obtained with the radishes. The young radish plants 

 were strongly attracted by the light, and in the morning they all 

 leaned at an angle of from 60° to 45° towards the lamp. During 

 the day they would straighten up, only to reach for the lamp again 

 on the succeeding night. This was repeated until the roots began 

 to swell and the plant became stiff. As the plants grew, the 

 foliage became much curled, and the amount of this injury was in 

 direct proportion to the nearness to the lamp. Those nearest the 

 lamp — within three or six feet — were nearly dead at the expira- 

 tion of six weeks, while those fourteen feet away showed little 

 injury to the leaves. The crops obtained in the dark or normal 

 house were about twice greater than those in the light compart- 

 ment. The entire plants and the tops were almost lialf lighter in 

 the light house, and the tubers were more than half lighter, while 

 the per cent of tubers large enough for market was as nine in the 



