668 



ELEC TR O- HOR TICUL TURE. 



greater was the acceleration. This tendency was par- 

 ticularly marked in the leaf-plants — endive, spinage, 

 cress and lettuce. The plants " ran to seed " before 

 edible leaves were formed, and near the light the leaves 

 were small and curled. This is well illustrated in spin- 

 age. Figs. 3 and 4. The cuts, which are made to the 

 same scale, show Round Dutch spinage when seven 

 weeks old. Fig. 3 shows an average plant from the 

 dark or normal house, and Fig. 4 one from the light 

 house within 7 ft. of the lamp. 



The electric light spinage matured and produced 

 good seeds while that in the dark house was still making 

 large and edible leaves with no indication of running to 

 seed. Some Landreth's forcing lettuce was grown in a 

 row nearly under the lamp. For three feet on either 

 side of the lamp, most of the plants were killed outright 

 soon after they came up, and the remaining ones in the 



Fig. ,j. Xukmal Si'i.\A(,e 1'lant. Fig. 4 (to the 

 right). One of the same variety and 



AGE, FROM THE LiGHT HoUSE. 



entire row (35 plants) were seriously injured, the leaves 

 curling and remaining very small. The plants increased 

 in stature, vigor 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; 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 dis- 

 tance from the lamp. 



It chanced that for a time two rows of endive grew 

 parallel to each other in the light house, but one stood 

 in full light while the other was shaded by an iron post 



an inch and a half in diameter. The result is well 

 shown in Fig. 6, page 670. The row to the left was 

 shaded, and the other received the full light. There 

 was a great difference between the two rows. The 

 average weights of the individual plants in both rows 

 after having grown two months in the light, at the given 

 distances, was, for eight plants in full light, average 

 weight, 49.5 grains ; for six plants in shade of post, 

 average weight 93.8 grains. 



An average plant in the dark house of the same age 

 weighed 575 grains, and it was larger leaved and darker 

 colored than those grown in the other compartment. 



These figures show at once the damaging influence of 

 the naked electric light upon plants near it. 



Some young radish plants on a high bench 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 plants 

 became stiff. As the plants 

 grew, the foliage became much 

 curled, and the amount of this 

 injury was in direct propor- 

 tion to the nearness to the 

 lamp. Those nearest the 

 lamp — within three to six feet 

 — were nearly dead at the ex- 

 piration of six weeks, while 

 those 14 feet away showed 

 little injury to the leaves. 



The experiment shows that 

 the crops obtained in the dark 

 or normal house were about 

 twice greater than those in the 

 light compartment. The en- 

 tire plants and the tops were 

 almost half lighter in the lightjhouse, and the tubers 

 were more than half lighter, while the per cent, of 

 tubers large enough for market, was as 9 in the light 

 house to 26 in the dark house. 



Peas in the light house, particularly those in direct 

 light, blossomed about a week in advance of those in the 

 dark house, and they gave earlier fruits ; but the pro- 

 ductiveness was less, being in the ratio of four in the 

 light house to seven in the dark house. The production 

 of pods (or flowers) was about the same in both houses, 

 but the plants in the light house produced only four- 

 sevenths as many seeds as those in the dark compart- 

 ment. 



EXPERIMENTS WITHOUT NATURAL LIGHT. 



To test whether injury was due to the electric light 

 itself or to continuous light during the whole twenty-four 

 hours, some lo-inch pots were inverted over radish 

 plants during the day and removed at night so that the 

 plants received no sunlight and about 12 hours electric 



