MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 211 



nach and endive went quickly into the formation of seed under the 

 same condition. This series of experiments was also lacking in re- 

 sults which gave any evidence that light directly retards growth. '^^ 



Corbett has recently published a paper upon the effects of an 

 illumination derived from incandescent gas-light upon plants. The 

 lamps furnished an illumination of about 560 candle power and a 

 study was made of the influence at various distances. It was con- 

 cluded that the effect of such light in supplementing the normal day- 

 light produced heavier and taller specimens of lettuce, and induced 

 faster growth of lettuce and spinach. Tomatoes produced flowers 

 and fruits earlier than under normal illumination, and lettuce and 

 radishes developed seed stalks earlier than under normal conditions. 

 The rate and period of growth were increased in lettuce and spinach 

 by the use of the supplementary artificial illumination. Lastly, the 

 proportion of sugar in solution in beets grown in such extended 

 illumination was greater than in the normal, although the size of 

 the beets was less. As a general result the growth of the shoot, 

 or the portion of it exposed to the light was greatly accelerated by 

 the additional illumination afforded by the experiments. ^^^ 



The entire life of the plant so far as the aerial organs is con- 

 cerned is one of wide experience in alternating periods of daylight 

 and darkness. The results of the experiments cited above demon- 

 strate with some certainty that increases in the total duration of illu- 

 mination to which a plant is exposed, during its vegetative period, 

 either by artificial nocturnal illumination, or by cultivation in Arctic 

 regions results simply in a correspondent acceleration of the sea- 

 sonal development of the plant, by which a greater amount of 

 work is accomplished within a given number of days. The ex- 

 tinction of the daily " resting period" brings no distinct reaction so 

 far as important anatomical features are concerned, although an ex- 

 aggerated production of certain substances is found to take place. 

 Neither is any retarding or paratonic effect to be seen as a result of 

 this continuous illumination. 



'5' Rane, F. Wm. Electro-horticulture Avith the incandescent lamp. Bull. No. 37, 

 W. Virginia Exp. Station. 1S94. 



'5^ Corbett, L. C. A study of the effect of incandescent gas-light upon growth. 

 Bull. No. 62, W. Virginia Exp. Station. 1899. 



See also Flammarion, C. Physical and meteorological researches, principally upon 

 solar rays, made at the station of agricultural climatology, Juvisy, France. Abstr. 

 Exper. Sta. Record, 10 : 103. 1898. 



