lO MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



Among the additional facts obtained it is to be noted that Veronica 

 speciosa developed normal flowers and fruits and also If omoea ■pur- 

 purea. A fruit of Cucurbita Pepo weighing 472.5 grams was pro- 

 duced in darkness. Seeds of this fruit, as well as those of Allium 

 porrium and Papaver somniferuni grown in darkness germinated in 

 the usual manner. I am constrained to call attention to the fact that 

 these results have not been confirmed by Amelung, who carried out 

 a similar series of tests in 1894. The general relations of light to 

 form and growth were considered in later papers by Sachs, and with- 

 out further discussion of his lengthly dissertations the chief conclu- 

 sions may be briefly stated as follows ; 



Light is not necessary for cell-division of non-green organs, but 

 is indispensable for organs containing chlorophyl. 



Exaggerated elongation of internodes is accomplished by increased 

 extension of the cells, not by multiplication of cells. 



The chief purpose of stems is to carry buds aloft to sunlight, and 

 most stems form greatl}^ elongated internodes when etiolated ; to this 

 may be noted the exceptions which fall into two groups. One in- 

 cludes plants with long slender internodes supposed to be normally 

 etiolated, and the other with compressed internodes which exhibit no 

 capacity for elongation.^' 



The development or non-development of flowers in darkness was 

 held to be dependent upon the presence of the special nutritive sub- 

 stances necessary for their growth. 



Plants with adequate supplies of special reserve material might 

 form normal flowers in darkness, but plants devoid of such reserve 

 material might perfect flowers only when a branch or leafy stem was 

 exposed to the light and could furnish the necessary constructive 

 material. 



The term photolonus was applied to the condition of the plant 

 when receiving illumination of a certain intensity sufficient to induce 

 a labile condition of the protoplasm. Under such conditions the 



3^ Sachs. Ueber den Einfluss der Lufttemperatur und des Tageslichts auf die 

 stundlichen und taglichen Aenderungen des Langenwachstums (Streckung) der Inter- 

 nodien. Arb. a. d. Bot. Inst. i. Wiirzburg, i : 99. 1872. 



Sachs. Vorlesungen ueber Pflanzenphysiologie. 1865. 



Sachs. Wirkung farbigen Lichts auf Pflanzen. Bot. Zeitung, 22 : 353, 361, 

 369. 1864. 



Sachs. Ueber die Wirkung der ultravioletten Strahlen auf die Bluthenbildung. 

 Arb. a. d. Bot. Inst. i. Wurzburg, 3 : 372. 1887. 



Sachs. Gesammelte Abhandlungen ueber Pflanzenphysiologie, 1 : 229, 261. 1892. 



