2IO MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



L. H. Bailey has carried out extensive experiments upon the in- 

 fluence of electric illumination of 2,000 candle power upon cultivated 

 vegetables and flowers in which the normal daylight illumination was 

 supplemented by that derived from electric arcs during nocturnal 

 periods of various lengths. The rays from a naked arc were injur- 

 ious to many forms and in the case of spinach it seemed to induce 

 the formation of flowers and seeds after the manner of certain other 

 agencies. The action of the light from shaded lamps was gener- 

 ally favorable to the growth of lettuce, while the effects on other plants 

 were of advantage economically, or not, according to the portion of the 

 body to be developed, and the general habit of growth. One of the 

 most important results of the experiments by Professor Bailey ^^^ was 

 that of attenuations similar to the " etiolations'"' of Bonnier were 

 produced (see Fig. 160). The rate of growth observed in the con- 

 tinuous illuminations afforded no proof that light retards growth. 



A comparative study of the injured and uninjured plants by Row- 

 lee showed that such leaves as those of coleus and heliotrope 

 were injured by the light from an arc lamp a yard distant, the effect 

 of the light being to kill the epidermal cells and hairs. Thick, 

 coriaceous, or succulent leaves with heavy cutinized external walls, 

 such as those of Ficus elastica, Rhododendron inaximiwi, Kalmia 

 latifolia, and coronilla were uninjured by such exposures, doubtless 

 owing to the screening effects of the heavy walls or cells contain- 

 ing much water. '^^ 



A series of experiments by Rane published in 1894 demon- 

 strated that the light furnished by incandescent lamps 60 to 80 candle 

 power did not give some of the injurious effects of arc lamps, and that 

 the growth of foliage plants for food was accelerated by such illumina- 

 tion. Flowering plants blossomed earlier and continued to form 

 flowers over a longer period than under normal illumination. Spi- 



'^^ Bailey, L. H. Some preliminary studies of the influence of the electric arc 

 lamp upon greenhouse plants. Bull. No. 30, Cornell Univ. Agric. Exp. Station. 

 1891. 



Bailey, L. H. Second report upon electro-horticulture. Bull. No. 42, Cornell 

 Univ. Agric. Exp. Station. 1892. 



Bailey, L. H. Third report upon electro-horticultiu-e. Bull. No. 55, Cornell 

 Univ. Agric. Exp Station. 1893. 



i*"Rowlee, W. W. Effect of the electric light upon the tissue of leaves. Proc 

 19th Annual Meet, of the Soc. for Promotion of Agric. Science, Boston, Mass., pp. 

 50-58, 2 pis. 1898. 



