ELECTRO-HOR TICUL TURE. 



light. Rubber tubing was conducted underneath the 

 pots and was connected with the hole in the bottoms in 

 such a manner that perfect ventilation was secured and 

 yet no light admitted. Seedling radishes, which had 

 never received sunlight, made a slender and sickly 

 growth, assuming a faint green color, but died in three 



Fig. 



5. Six Best Tubers of Scarlet Frame Radish from Dark 

 Light Houses. 



or four weeks. None of the radish plants succeeded in 

 making a third or true leaf. 



Another series of tests was made by covering well 

 established plants in the beds. A tight box 18 inches 

 square and a foot high was placed over certain plants 

 during the daytime, and was removed at night and 

 placed over contiguous plants of the same kind. Thus 

 one set of plants received only electric light and one 

 only sunlight, and inasmuch as both were covered during 

 half of the twenty-four hours, any error which might 

 have arisen from the covering itself — as lack of ventila- 

 tion and increased heat — was eliminated. February 7th 

 certain radishes in the light house which had been 

 planted two weeks were covered. In eight days some of 

 the plants which were covered during the day were dead 

 and the remaining ones were very weak. At the same 

 time, those which were covered during the night had 

 made a better growth than they had before and better 

 than contiguous plants which had not been covered. An 

 examination of the leaves of the plants receiving only 

 the electric light showed that they contained no starch 

 and very little or no chlorophyll. 



On February r5th two strong plants of German ivy 

 fSenefio scam/ens), carnation and begonia, were selected 

 for a similar experiment. One plant of each was cov- 

 eredby day and the other by night. February 2S the 

 electric light ivy appeared as if dying, and March 10 

 it was apparently dead. By March 3 the electric light 

 carnation was seen to be making an etiolated growth. 

 A month later the new white growth had become four 

 to six inches long. The electric light begonia began to 

 drop its leaves March 5th, and a month later all the 

 leaves had fallen. The contrasts were most striking. 

 The daylight plants were strong and dark colored, while 

 the others were dead or nearly so. 



The above experiments show conclusively that within 

 the range of an ordinary forcing-house the naked arc 

 light running continuously through the night is injurious 

 to some plants : and in no case did we find it to be 

 profitable. But the fact that the light hastens maturity 

 or seed-bearing suggests that a modified light may be 

 useful under certain conditions. 



experiments with a pro- 

 tected LIGHT RUNNING 

 ALL NIGHT (1890). 



Early in March. 1890, an or- 

 dinary white opal globe was 

 placed upon the lamp, and for 

 five weeks experiments similar 

 to those already described were 

 conducted. The effect of the 

 modified light was much less 

 marked than that of the naked 

 light, Spinage showed the 

 same tendency to run to seed, 

 but to a much less extent, and 

 the plants were not affected by 

 proximity to the lamp. Let- 

 tuce, however, was decidedly 

 ight house. 



better in the electric 



Varietn'. 



Half-long Rose 41 oz. 



26 



Scarlet Globe 24 



Prussian Turnip 28 



27 



Blood-red " 36 



French Breakfast 25 



Half-long Scarlet 22 



Average weight o 

 entire plant. 

 Light 

 house. 



A\'erage weight 

 of top. 



Average 



X'arieties. 

 Half-long Rose . . 



.29 oz. 



house. 

 .22 oz. 

 .14 " 



Dark 



Light 



Da> 



house. 



house. 



house. 



.41 oz. 



.190Z. 



.160Z. 



■34 " 



.12 " 



.14 " 



.26 " 



.08 " 



.u8 " 



.29 " 



.11 " 



• oy " 



•33 " 



.09 " 



.oS ■' 



.40 " 



.14 " 



•15 " 



•30 " 



•13 " 



.n " 



•3- 



.oS " 



.08 " 



•33 oz. 



.12 oz. 



.11 oz. 



weight 



No. of marketable 



ers. 



tubers. 



Dark 



Light 



Dark 



house- 



house. 



house. 



.250Z. 



84 pet. 



97 pet. 



.20 " 



76 



37 " 



.iS " 



88 " 



95 " 



20 " 



100 " 



100 " 



•-5 



90 " 



too " 



■-5 



90 " 



75 " 



.19 



100 ' ' 



100 ■ ' 



•-H " 



S5 " 



100 



.-'2 oz. 



89 p.ct. 



94p,ct. 



Scarlet Globe 16 " 



Prussian Turnip 17 " 



18 " 



Blood-red " 22 " 



French Breakfast 12 " 



Half-long Scarlet t4 " 



Average 170Z 



The loss due to the electric light averages from one to 

 five per cent, in the different comparisons, while the 

 loss occasioned by the naked light was from 45 to (35 per 

 cent. It is noticeable, also, that while the tops or 

 leaves were lighter under the naked light, they were 

 heavier under the modified light than those of normal 

 plants ; and this is interesting in connection with the 

 fact that the lettuce did better under the modified light 

 than in the dark house The carrots gave indifferent re- 

 sults. They did not appear to be affected greatly even 

 by the naked light, even when growing directly opposite 

 to it and but three or four feet away. Carrots require 



