The percentages of 



234 



0.31; top, 0.0« and 0.14; tubers, 0.07 and 0.16. 

 marketable tubers were 27 and 78. 



Tho table sh^ws that the crops obtained in the dark or normal house were about 

 twice as large as those in the light compartment. The entire plants and the tops 

 were almost hallligliter in the light house, 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. And it should also be said that the average size of the tubers 

 graded as marketable was less in the light house than in the other. * * * 



A chemical analysis of samples of radishes from the light house (in both full light 

 and shadow) and the dark house gave the following results : 



Tlifsr lignns sliow lliiil the plinils iiiMb r tbi- <l<c1iic light liad reached a gr<a1<r 

 degree of maturity than those in the niirnial or dark liiiuse. * » * 



[Dwarf peas were giown on two bcnclns, one of which shaded about half of the 

 other.] In the shaded portion tlie peas wen- hirger and more productive than those 

 in full light, although the latter were farther from the. lamp. The average heights 

 of plants were as follows: Light house, in full liglit, 4.8 inelu's; liglit liouse. in 

 shade, ii.^inihes; dark house. .^.S inches. The jdants in the light house, jiarticularly 

 those in direet liglit, blossomed about a week in advance of tliose in the dark 

 house, and they gave earlier fruits, but the productiveness was less, being in tlie 

 ratio of 4 in the light house to 7 in the dark house. The decrease in production was 

 due largely to the fewer number of peas in each pod, for the number of fruitful 

 pods produced in each case was as 7 in the light house to 9 in the dark house, and 

 there were many seedless pods in the light house. In other words, the produc- 

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

 light liouse produced only four sevenths as many seeds as those in the dark compart- 

 ment. 



The question whetlier the injurywas due to the electric lijjht its«'lt<»i 

 to continuous light during; the whole twenty tour hours, was tested with 

 various plants. At first seedling radishes were covered with pots dur- 

 ing the day and exposed to the ('lectric light for about 11* hours at 

 night. These made a slender and sickly growth, assuming a laint green 

 color, and died in 3 or 4 weeks. 



"Tlie ex])('riincnt was now coiKluctcd ui>on a larger scale, ami at a 

 time when llic hours ol" sunlight were about crpial to tlie hotns ot elec- 

 tric light. A tight wooden frame was placed upon the soil of a beiicli 

 at one end of the light house. This frame was provi<led with a tiglit 

 cover which Mas kei»t on during the day and removed at night." Kadi.-^li 

 seeds ])lanted in this manner, both in soil and in ]>ots, germinat«'d and 

 made a very lapid, sjiindling, and nearly colorless growth for a short 

 time, but in 3 or 4 weeks the young plants were all dead. Similaj 

 results were obtaim'd Avitli h'ttuce, licans. corn, and ]tol;itoc.s. 



