24 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



tory quotient of etiolated leaves varies from .72 to .76, in a water cul- 

 ture, it ranges from .6^ to .65 and in a culture of sugar about .76. 

 The respiratory activity of both normal and etiolated leaves decreases 

 after confinement in darkness for prolonged periods. 



Palladine saw in the form of etiolated plants a direct adaptation 

 to the altered transpiratory conditions resulting chiefly from the 

 absence of light, and points out that the anatomy of etiolated stems 

 is much like that of stems grown in chambers with a saturated atmos- 

 phere. A chemical analysis of etiolated plants showed them to be 

 capable of division into two groups. One group, including the stem- 

 less plants contains less proteids than green organs, and the second 

 includes plants with stems, the leaves of which contain more proteid 

 than the normal, while the stems are depleted of this substance. 



In some experiments upon the formation of green color and growth 

 with separated etiolated leaves, Palladine found that the formation of 

 chlorophyl in etiolated leaves is accomplished only when a supply 

 of sugar is at hand, and that lack of calcium will prevent the devel- 

 opment of leaves of Vtr/a Faba. 



Lamarliere -' concluded that the differences in the structure of 

 leaves in diffvise light from those in direct sunlight corresponded 

 ■directly to the diminished functions of respiration, food-formation 

 and transpiration in the former instance. 



C. DeCandolle repeated the experiments of Sachs in testing the 

 influence of the ultra-violet rays, and his results partly confirmed the 

 conclusions of Sachs that these rays are necessary for the construc- 

 tion of specific substances used in the formation and growth of 

 floral organs. The rays in question were excluded from the plants 

 by solutions of quinine and aesculine, and since some flowers were 

 formed on the screened plants a stimulative action of the ultra-violet 

 rays was suggested. ^- 



Frank^'^ recognized the futility of attempts to make generaliza- 

 tions on the influence of light upon growth in his text-book in 1892, 

 and concluded that etiolation phenomena are exhibited only by 

 organs, the activity of which is concerned with the sun's rays. He 

 saw in etiolation an effort to carry organs up to sunlight to the func- 



^1 De Lamarliere, L. G. Recherches phj'siologiques sur les feuilles ddvellop^es 

 a I'ombre et au soleil. Rev. Gen. d. Bot. 4: 481- 1892. 



S'! DeCandolle, C. Etude de Taction des rajons ultra-violet sur la formation des 

 fleurs. Arch, des Sc. Phys. et Nat. Geneve, 28: 265-277. 1892. 



"3 Frank, B. Lehrbuch der Botanik, i : 389. 1892. 



