April, 19 lo 



AMERICAN HOMES AND GARDENS 



155 



of the screens, the dif- 

 ferences between the 

 temperatures of the houses 

 never exceeded 3 deg. C. 

 (37-4 tleg. F.j. In the 

 second series of experi- 

 ments, as in the first, the 

 plants in the red house 

 grew much more rapidly 

 than those in the white, al- 

 though the temperature was 

 about the same in both. 

 J he radiometer showed 

 that the illumination was 

 the same in the screened 

 white house and the un- 

 screened red house. Hence 

 the increased growth under 

 the red glass must be attri- 

 buted to a specific action of 

 the red rays. M. Flam- 

 hibited certain peculiarities. Very little growth was made marion has also succeeded in modifying the forms, sizes 



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The I 



our glass houses 



he 



under blue, green or colorless glass, while in the red house 

 the plants developed rather more rapidly, but their stems 

 were blanched. Lettuce plants in the red house sent up 

 stalks live feet in height, while the plants under white 

 glass remained headed, and only two feet high. 



Several objections, however, suggest themselves in re- 

 gard to this method of experiment. In the first place, 

 the intensity of illumination is different in each house, 

 the white house being the lightest and the blue house the 

 darkest. Secondly, the temperature is subject to a similar 



and colors of fiowers and leaves, and the perfumes ot 

 flowers, by the employment of colored glasses. 



Geranumi leaves, for example, lost their circular russet 

 markings, and became large, deeply incised and pale green 

 under red glass, nearly circular and dark green under the 

 blue, and small and very pale under the green. Similar 

 results were obtained with fruits, including peaches, apples 

 and cherries. 



In regard to the development of perfumes under the 

 influence of colored rays, M. Flammarion obser\ed a great 



variation, the highest temperatures having been observed increase in fragrance of strawberries under red glass. 

 under the colorless glass, and the lowest under the blue. Flowers of Crassitla exposed to the open air, either in sun- 

 Now, there are for each species a temperature and a degree shine or in shade, possess little fragrance, but flowers ot 

 of illumination which are the most favorable for the growth the same individual plant covered with colored bell glasses 

 of the plant. develop a delicate perfume resembling the scent of the 

 In order to separate the effects produced by the three banana. When these flowers are cut and put in vases, they 

 factors, color, illumination and temperature, M. Flam- retain this perfume, and partially regain the red color 

 marion repeated the experiments described above, employ- which they lost under the colored glasses. 

 ing screens to moderate the temperature and illumination The various rays of the solar spectrum not onlv modify 

 in certain cases. By this means he succeeded in making the longitudinal growth of plants, but affect the entire vege- 

 the temperature and illumination of the red house equal tative system. The roots, for example, are poorly devel- 



to those of the white house. The luminous intensities were 

 measured with vapor actinometers and Crookes' radio- 

 meters. The temperatures of the soil were obtained by 

 means of self-registering spirit thermometers, the bulbs of 

 which were buried to depths of 10, 20, 30 and 60 inches, 

 and a horizontal self-registering instrument gave the tem- 

 perature of the surface. 



oped under all the colored glasses, especially the blue. As 

 the nutrition of plants depends to a great degree in the 

 development of their roots, it is e\'ident that the plants in 

 the white glass house derive most nutriment from the 

 soil. This partly explains the lack of vigor observed in 

 the plants of all the colored glass houses. JNI. Flammarion 

 has observed differences in height, vegetative activitv. 



It was thus shown that the differences in growth in the strength, sensitiveness, coloration and even anatomical 

 foregoing statement could 

 not have been due to differ- 

 ences in temperature, for 

 the comparatively 1 o w 

 temperature of the blue 

 house was the most favor- 

 able to growth. Even here 

 the thermometer some- 

 times rose to 40 deg. C. 

 (104 deg. F.), a tempera- 

 ture higher than common- 

 ly used in horticulture; 

 while those between 45 and 

 50 deg. C. (113 and 112 

 deg. F.), which were occa- 

 sionally observed under the 

 white and red glasses, ap- 

 pear unfavorable to vege- 

 tation. After the addition Self-registering thermometer for the determinalioii of soil tempeiatures. 



