l8 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



1890, to which no reference will be made here; a full discussion is 

 given in the monographs of Elfving and Grantz."" 



Rauwenhoff ^' made extensive investigations of the relations of 

 light to form, and development of tissues, a preliminary notice of 

 which was published in 1876 and the full account in 1878. He con- 

 cluded that not only the pith but the entire fundamental tissue par- 

 ticipated as active factors in the excessive lengthening of stems. 

 He regarded the theories of Kraus and also of Batalin regarding the 

 small size of etiolated cotyledons as untenable. The lack of thicken- 

 ing of walls, and the non-development of the wood and sheath in 

 the fibrovascular bundles was noted. The theories of the correlation 

 existing between the root and shoot by which the former showed a 

 decreased development in etiolated specimens were not confirmed. 

 Rauwenhoff concluded that leaves exhibiting marked dorsiventrality 

 were most likely to remain small in etiolation. The anomalous 

 structures of etiolated plants were ascribed to the action of negative 

 geotropism, unhindered by heliotropism. Lastly Rauwenhoff re- 

 garded etiolation as a pathological phenomenon. 



Stebler''^ attempted a refutation of the theory of Sachs as the 

 universal prevalence of a daily periodicity of growth. Stebler 

 accepted the conclusion that light may retard growth, but found that 

 the greatest increase in monocotyledonous leaves occurred during 

 the most intense illumination, and that this growth is intimately con- 

 nected with food-formation. Such daily maxima also occurred at a 

 corresponding part of the middle of the day in etiolated specimens. 

 Dicotyledonous leaves exhibited the most rapid growth in the middle 

 of the forenoon, which continued until the favorable influence of 

 rapid food-formation was counterbalanced by the retarding influence 

 of light. The decreased and decreasing rate continued until the 

 following morning when assimilation was again resumed. The 

 difference in the behavior of the two forms of leaves was due to the 

 location of the growing region, which is basal in the linear mono- 

 cotyledonous type and is shielded from the direct action of the rays. 



™Elfving, F. Studien ueber die Einwirkung des Lichts auf die Pilze. Helsing- 

 fors. 1890. 



Grantz, F. Ueber den Einfluss des Lichtes auf die Entwickelung einiger Pilze. 

 Leipzig. 1898. 



6' Rauwenhoff, N. W. P. Sur les causes des formes anormales des plantes. Ann. 

 Sc. Nat. VI. 5 : 267. 1878. 



" Stebler, F. G. Untersuchungen iiber das Blattwachstum. Jahrb. f . Wiss. Bot. 1 1 : 

 47. 1878. 



