MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 27 



lack of it, a supposition parallel to and corroborative of the theory of 

 Godlevvsky. Goebel's general discussion of the subject in his Organ- 

 ography will be considered in a later section of this memoir. 



Klemm ^^ concluded that light is not necessary for the existence 

 of protoplasm, and a certain maximum intensity acts unfavorably and 

 fatally, producing granulation and rigor, but not vacuolization. Such 

 action is not so marked as with heat radiations, however. 



The behavior of aquatic plants in darkness offers some interesting 

 data, especially those offered by the seed-plants. Mobius ^^ found that 

 Cerato^hylhmi showed excessive elongation of its internodes, and 

 placed the leaves in a drooping position, as well as the branches. 

 The excessive length of the internodes was correspondent to an ex- 

 cessive elongation of the cells, and no multiplication occurred. The 

 movement by which the tips of the leaves and branches are curved 

 toward the base of the stem is caused by internal forces and is not 

 geotropic. Similar reactions were obtained from Myrio^hylliun. 

 Ranunculus divaricaius did not exhibit marked change. Excessive 

 elongation of internodes was also shown by Elodea. 



The effect of light upon bacteria and similar organisms has been 

 the object of several important investigations, a history of which is 

 given briefly by H. M. Ward ^^ in the latest paper on the subject. 

 The results obtained by the various workers are by no means in 

 agreement, but it seems fairly well established by Ward that blue, 

 violet and ultra-violet rays exert a fatal effect upon vegetative 

 cells of bacteria and yeasts. These results, however, only have the 

 general significance that the optimum intensity of light for the organ- 

 isms in question is far below that of direct sunlight. 



The results of continuous illumination, as described by Bonnier, 

 are curiously parallel to those of continuous darkness, according to 

 the observations of specimens exposed to the light of electric arcs. 

 Among other features of interest it was noted that the structure of 

 the leaf was more simplified than in the normal, that the epidermal 

 tissues of the petioles were less highly developed, sclerenchymatous 

 elements being lacking, that the structure of the stems was much 



95 Klemm. Desorganizationserscheinungungen der Zelle. Jahrb. f. wiss. Bot. 28 : 

 627. 1S95. 



96 Mobius, M. Ueber einige an Wasserpflanzen beobachtete Reizerscheinungen. 



Biol. Centralb. 15 : 1. 1895. 



»MVard, H. M. The Action of Light on Bacteria. Proc. Roy. Soc. 185 : 961. 



1S95. 



