272 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



after an advanced stage of development had been reached is clearly 

 not an etiolative reaction in any sense of the word. In an- 

 other series of observations, by means of partial etiolations, the 

 apical portions of shoots were thrust into dark chambers, and in 

 some instances new flower buds of Cucurbita and Petunia arose 

 on branches from which light had been excluded in this manner, 

 which came to a development more or less nearly approximating the 

 normal, except in the matter of color. As a result of these facts 

 Sachs concluded that the development of flowers was dependent 

 upon peculiar substances resulting from the action of light on chlor- 

 ophyl-bearing tissues, and that the failure of etiolated plants to pro- 

 duce flowers was due to the lack of such material. In partial etio- 

 lations an opportunity was afforded for the production of this specific 

 material in the illuminated leaves, which then might be easily con- 

 ducted to the flowers much in the same manner as under normal 

 conditions. An etiolated flower grown under the above conditions 

 was fertilized from pollen grown in the open, with the result that a 

 ripe fruit was finally produced in the dark chamber that weighed 

 3 kilos, (Given as 4 kilos in Sachs' Phys., p. 533. 1887.) Seed 

 was also produced on a number of other species by similar " partial 

 etiolations." In a later investigation Sachs '-' believed to have demon- 

 strated that the ultra-violet rays furnish the energy by which a speci- 

 fic anthogenic substance is formed and without which these organs 

 are not produced.^-'* 



C. DeCandolle repeated Sachs' experiments in 1892, cultivating a 

 number of plants in light which in one series had passed through a 

 layer of water, and in another through a layer of sulphate of quinine 

 or aesculin by which the plants were screened from the action of the 

 ultra-violet rays in the latter. " He found no flowers in two plants 

 after cultivation behind a screen of solution of sulphate of quinine for 

 seventy-one days ; thirty-three flower buds in two plants grown be- 

 hind an equally thick screen of water ; behind a screen of aesculin 

 flowers were formed in Lobelia erinus, but in smaller numbers than 

 behind water.'"'*'' The results in question are not conclusive that the 



'^^ Sachs. Ueber den Einfluss des Tageslichts auf Neubildung und Entfaltung ver- 

 schiedener Pflanzenorgane. Bot. Zeitung, 21 : Beilage, p. 31, 1S63, and Wirkung des 

 Lichts auf die Bliithenbildung unter Vermittlung der Laubblatter. Bot. Zeitung, 23 : 

 1865. 



i''^ Sachs. Ueber die Wirkung der ultravioletten Strahlen auf die Bliithenbildung. 

 Arb. a. d. bot. Inst. i. Wurzburg, 3 : 372. 1S87. 



'^^Goebel. Organography of Plants. Part I. p. 244. 1900. 



