MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 33 



Ricome"^ has made a series of examinations of the behavior of 

 etiolated plants placed in light before deterioration of the shoot had 

 begun and his chief results are as follows : The excessive growth 

 in length of stems slackens quickly when etiolated plants are illumi- 

 nated and the rate of growth remains slower than that of control 

 specimens. If, however, abundant reserve material is at hand the 

 rate is not sensibly slower than the normal, except at the beginning 

 of the illumination. Mature shoots of illummated etiolated specimens 

 are longer than normal if such reserve material is present, but shorter 

 otherwise. The internodes at the base of the hypocotyledonary axis 

 are more slender than the normal in such plants unless ample reserve 

 material is present. The basal internodes formed in darkness are 

 elongated in light but the internodes formed immediately after 

 exposure seem to be shorter than the normal, or those formed later 

 above them, which have the normal length. This seems to be due 

 to the disturbances in the transpiratory conditions. The number of 

 leaves of illuminated etiolated specimens is less than in normal 

 specimens. Etiolated plants without reserve food do not attain the 

 normal weight when illuminated, although this is accomplished by 

 plants with a reserve food-supply. Illuminated etiolated plants have 

 a comparatively greater dry weight than normal specimens. If plants 

 with reserve food are etiolated for a short period and then illumi- 

 nated they will appear more vigorous than normal specimens for 

 some time, a result that has been confined by Dr. H. M. Richards 

 in some experiments in his own laboratory. 



Noll '^^ concludes that darkness as such acts as a positive stimulus 

 in producing etiolation phenomena and finds that similar reactions 

 may be obtained from other causes, such as in the growth of roots in 

 solutions lacking nitrogen. Phenomena resembling etiolation have 

 been induced in algae by Benecke "" by the use of culture solutions 

 lacking nitrogen. 



Wiesner ^"** likewise was able to secure excessive elongations of 



"' Ricome, M. H. Sur le developpement des plantes etiolees ayant reverdi a la 

 lumiere. Compt. Rend. 131 : i-5i- 1900. 



Ricome, M. H. Action de la lumiere sur les plantes preablement dtiolees. Rev. 

 Gen. d. Bot. 14: 26, 72, 120. 1902. 



"8 Noll, F. Ueber das Etiolement der Pflanzen. Sitzungsber. d. niederrheim 

 Ges. z. Bonn. May, 1901. Abstract, Botan. Ztg. 60: 38. 1902. 



'i** Benecke, W. Ueber Cultur Bedungungen einiger Algen. Bot. Ztg. 56: ist 

 Abth. 89. 1898. 



lio Wiesner, J. Formanderungen von Pflanzen bei Cultur im ahsolut feuchten 

 Raume. und im Dunkeln. Ber. d. Deut. Bot. Ges. 9 : 46. 1S91. 



