MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 273 



ultra-violet rays take a part in the construction of any specific ma- 

 terial. All of the phenomena in question might well be ascribed to 

 the stimulative action of light as suggested by DeCandolle. So far 

 as the relation of the screened and control plants are concerned ex- 

 periments of this character must be made with the greatest care, since 

 a small difference in the intensity of illumination might inhibit or in- 

 duce flower-formation irrespective of the actual composition of the 

 spectrum. Here as in other operations of the plant, the formation of 

 flowers or reproductive bodies requires a certain optimum intensity 

 of illumination and any variation beyond certain limits will have 

 the consequence that such activity will not ensue, a conclusion well 

 justified by the careful researches of Vochting,'*'' who found that 

 light sufficient for the normal vegetative activity of a plant did not 

 necessarily coincide with the amount necessary for the formation of 

 flowers. A repetition of Sachs' "partial etiolations" with Cucur- 

 hiia by Amelung, in 1893, gave results in accordance with those pre- 

 viously obtained by the former in so far as the production of flowers 

 and fruits was concerned. Flowers of fairly normal aspect developed 

 from young buds placed in darkness, but the flowers which arose 

 entirely in darkness attained a lesser size as the distance from the 

 illumination portion of the stem increased. The earliest functional 

 atrophies were found in pollen, the etiolated cells of which were in- 

 capable of carrying out the fertilization processes, the stamens show- 

 ing more marked effects of the confinement in darkness than the 

 pistils. The size of etiolated pollen grains varied from a diameter 

 of 22 to 29, while that of normal grains ranged between 26 and 27. 

 The extine, intine and cytoplasm gave a fairly normal appearance 

 when treated with Grenacher's borax-carmine, but the two nuclei 

 had undergone such degeneration as to have disappeared, or per- 

 haps but one remained. The gametophyte hence appears to sustain 

 general relations to light similar to that of the spores of ferns. ^*® 



The researches of Askenasy,^^^ which were made by means of 

 various imperfect and partial etiolations, led him to conclude that the 

 non-development of flowers in darkness was due to the lack of a 

 proper amount of food- material in the shoot, rather than to the ab- 



^8' Vdchting. Ueber den Einfluss des Lichtes auf die Gestaltung und Anlage der 

 Bliithen. Jahrb. f. wiss. Bot. 25 : 149. 1893. 



18* Amelung, E. Ueber Etiolement. Flora, 78 : 204. 1S94. 



i^^Askenasy, E. Ueber der Einfluss des Lichtes auf die Farbe der Bliithen. Bot. 

 Zeitung, 34 : 1,27. 1876. 



