October 5, 1892.] 



Garden and Forest. 



479 



cess in providing Easter flowers and plants of tlie highest 

 class. One lot of 20,000 potted Bermuda Lilies was an indica- 

 tion of the quantify in which plants are grown here. 

 Elizabeth, N.J. J. N.Gerard. 



Recent Publications. 



Something more than a year ago we published a con- 

 densed account of some experiments which Professor Bailey 

 had made, to ascertain the effect of electric light upon plants 

 grown in glass houses. Lettuce appeared to be greatly assisted 

 by the light, and some ornamental plants produced earlier 

 and brighter flowers under its influence, while some plants 

 were affected injuriously. In these first experiments, the arc 

 lamp hung inside of the house, and it was found that when the 

 arc was screened by an opal globe or a pane of window glass, 

 better results were obtained. This suggested the inquiries, (i) 

 whether the glass roof itself would not furnish an appropriate 

 screen, so that the light could be hung above it, and (2) if this 

 were true, how much glass could one light profitably cover? 

 Without explaining the methods of screening the check 

 plants, it is enough to say that an electric street-lamp was sus- 

 pended over a greenhouse, and Bulletin 42 of the Cornell Univer- 

 sity Experiment Station contams a record of its effects upon a 

 few common plants. 



The benefit to Lettuce was quite as apparent this year as it 

 was last, so that there can be no doubt as to the advantage of 

 the electric light, in forcing it. Indeed, Mr. W. W. Rawson, 

 of Arlington, near Boston, uses electric lights, which are run 

 all night for the commercial forcing of Lettuce. Mr. Rawson 

 estimates that he secures a gain of five days in a crop of Let- 

 tuce, by using this light, and as he grows three crops during 

 the winter the total gain is two weeks of time. The gain from 

 one crop is estimated as sufficient to pay the cost of running 

 the lights all winter, and the effect of a 2,000-candle power 

 lamp is marked at a distance of one hundred feet. 



At the Cornell Station light was started on the 19th of Octo- 

 ber above some Boston Market Lettuce, four weeks old, and 

 some seedling plants of Landreth's Forcing Lettuce, which 

 were just beginning to show above the soil. The lamp seldom 

 burned after eleven o'clock and often ran but an hour or two, 

 and on moonlight nights it was not used at all. The house 

 was exposed to sunlight during the day, in addition to this 

 small and varying supply of electric light. A house which 

 was lighted by the sun, but received no light at night, was used 

 as a check. A clear glass globe surrounded the lamp, so that 

 the light passed through two panes of glass, that is, the globe 

 and the roof, before it reached the plants. In a single week 

 after the light was started, the plants of Boston Market Lettuce 

 began to excel those in the unlighted house, and when forty 

 hours of electric light had been expended on them they were 

 percepfibly ahead of the others. The plants directly under the 

 light and from seven to ten feet from the arc were the earliest 

 to show their superiority. On the first of November the 

 hghted plants were one-fourth larger than the other, and 

 showed a marked tendency to turn toward the light. The 

 plants even in the farther extremity of the lighted compart- 

 ment gained steadily throughout the experiment and were 

 ready for market a week or ten days before those in the un- 

 lighted house, while in quality the Lettuce was indistinguish- 

 able from that grown under ordinary conditions. 



Small plants of Landreth's Forcing Lettuce, which stood 

 where they had been sown, behaved differently from the trans- 

 planted Lettuce. For the first week they were stunted, not- 

 withstanding the fact that they Avere farther from the lamp 

 than the Boston Market Lettuce plants which did so well from 

 the outset. After some days of lingering, when the plants be- 

 gan to acquire three or four leaves, they rapidly recuperated 

 and finally overtook their companions in the unlighted house, 

 but they never showed the superiority which the transplanted 

 ones exhibited. Professor Bailey does not attempt to give 

 the reason for this behavior, although he had observed it be- 

 fore, and other experimenters have reported similar results. 

 He considers it sufficient for his present purpose to say that it 

 appears to be better to sow Lettuce under common conditions 

 and then transplant the seedlings under the light after they 

 are well established. 



The extremity of the light compartment was forty feet away 

 from the lamp and the roof is low, so that much of the light 

 was reflected from it, and yet at this distance, where there was 

 nothing but diffused light, the plants were much better than in 

 the unlighted house. The experiment was repeated with 

 second and third crops of Lettuce and with several varieties 

 with similar results. On one bench Radishes had been planted 



among the Lettuce and the interception of the light by the 

 Radish-leaves had a marked effect on the Lettuce-plants which 

 stood behind them, that is, these shaded plants were much 

 smaller than those fully exposed to the light. When the 

 Radishes were removed the shadows of the Radish-leaves ■ 

 could be traced on the Lettuce, and the same result was seen 

 where the shadow of a rafter lay across the plants. 



In the earlier experiments Radishes under the naked light 

 were uniformly injured, and when the light was protected by 

 an opal globe injury was still apparent, although it was de- 

 creased, that is, the tubers lost only from one to five per cent, 

 in weight, while the weight of the leaves was increased. This 

 year, under light which was strained through both a globe 

 and a glass roof, there was an increase both in the tubers and 

 in the tops. The best results were obtained from the sash di- 

 rectly under the light, where the tubers were more and larger 

 and the tops were less. In no cases, however, have Radishes 

 been sufficiently benefited to pay for the cost of the light. 



Early Egyptian Beets were sown in the lighted and unlighted 

 houses, and a month later, after 160 hours of electric light, the 

 Beets in the lighted compartment were one-third larger than 

 the others. Five months after sowing it was found that fifty- 

 seven per cent, of the plants gave marketable tubers against 

 only thirty-three per cent, of those in the dark house, and the 

 total average weight of the plants in the fight was about one- 

 half an ounce greater than the weight of those in the dark 

 house. The test of Beets, however, was not a decisive one, 

 because the plants in the dark house received more bottom- 

 heat than the others. 



Last year, under the naked light. Spinach ran directly to seed, 

 while plants in the unlighted beds made good edible leaves. 

 In the present experiment, a month after the light had been 

 shining an average of five hours a night, all tlie Spinach in 

 the lighted house was ten to fifteen per cent, larger than in the 

 unlighted beds, and there seemed to be no greater disposition 

 to run to seed in the one case than in the other. This advan- 

 tage was maintained throughout the experiment. The result 

 was unexpected since in the first experiment this crop was 

 very much injured by the light. This test seems to indicate 

 that two panes of glass between the light and the plants have 

 a remarkable influence. 



Of Cauliflower it is sufficient to say that under the light they 

 tended to grow taller than in ordinary conditions, but they 

 made fewer and smaller heads. 



One hundred Violets were set in beds a few days before the 

 light was started, twelve to sixteen feet from the lamp. Fifty 

 plants were covered every night with a black enameled cloth 

 box, while provision was made for giving them ventilation, 

 and fifty others received the light. In three weeks after the 

 light was started the exposed plants began to bloom, while no 

 buds could be found on the darkened bed. It was not until 

 five weeks after the starting of the light that a flower appeared 

 on the darkened plants, while the others condnued to bloom. 

 Twenty-five strong plants of the Daisy (Bellis perennis) were 

 placed fifteen to twenty feet from the lamp, where the light 

 was rather weak. Twenty-five others were placed in an un- 

 lighted house. In the first lot, flowers appeared four weeks 

 after starting the light, and for a month or six weeks thereafter 

 these plants bloomed more profusely. At that time the dark- 

 house plants began to surpass the others in the number and 

 size of their flowers and the vigor of the plants. In other 

 words, the lighted plants bloomed earlier, and never made 

 such a stocky growth, and soon exhausted themselves. It is 

 possible that they might have endured longer if they had been 

 established in beds for a longer time before the light was put 

 upon them. 



Most interesting were the observations as to the time when 

 plants make their growth. It has been held that plants grow 

 chiefly at night, when they use the material which they have 

 manufactured during the hours of sunlight. It was natural, 

 therefore, to inquire when the lighted plants grew, and whether 

 they grew more rapidly during their fewer hours of darkness, 

 or whether they grew when the light was burning. By careful 

 measurement and record it was found that Lettuce-plants 

 grew about as much under normal conditions in daylight as in 

 darkness, and the periodicity of growth was very irregular. 

 The leaves of the Lettuce grew more rapidly in the lighted 

 house for the first week or so, after which their growth be- 

 came greater in the dark house — that is, the leaves matured 

 more quickly under the light. The records show that the elec- 

 tric light did not determine periodicity of growth ; that increase 

 under the light occurred only during the first days, and that 

 growth in both houses took place in daylight as well as in 

 darkness. 



Professor Bailey's first bulletin concluded with these words : 



