84 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



length of nearly a meter, bearing branches or buds at distances of 3 

 to 8 cm., the distance from the bulb to the first and lower branch 

 being slightly in excess of that of the normal. In some places, how- 

 ever, the intervals w^ere so short that three or four branches were 

 crowded on a portion of stem not more than a centimeter in length. 

 In some instances the buds developed branches 6 to 8 mm. long, sub- 

 tended by small bracts of equal length. A bract about 7 cm. long, 

 perfectl}^ white, was formed at the base of each stem, being about 

 double the normal length. ^^' 



A comparison with the normal shows that an excessive elonga- 

 tion has taken place in the basal portion of the shoot, and that the 

 development of the terminal portion has been hindered and the 

 growth of the branches almost totally suppressed. The plant is 

 normally a twiner, clinging closely and firmly to supports, but the eti- 

 olated specimens were unresponsive to the pres- 

 ence of vertical supports and were held to It by 

 means of cords. The terminal portions of the stems 

 exhibited an apogeotropic reaction. 



The thickening of the outer walls of the epi- 

 dermis was notably less in the etiolated examples. 

 Stomata were present, and were open when exam- 

 ined in water. The layer of parenchymatous tissue 

 beneath the epidermis, which usually contains 

 many chloroplasts and starch granules in the nor- 

 mal plant was almost free from plastids and solid 

 bodies of all kinds in the etiolated examples. The 

 sclerenchyma ring internal to the cortical tissue is 

 but slightly thickened, and the fibro vascular tissues 

 show but little development. 



Brassica campestris L. 

 Large turnips were placed in the dark room in 

 February and the leaves were soon sent out, grow- 

 ing very rapidly and attaining full size by the end 

 of March. The shoots reached a total height of 

 55 cm. Leaves attained a length of 13 cm., of which 

 4-6 cm. lay in the petioles. The narrow laminae 



' 13' For a general description of the development and growth of Botviea see Buche- 

 nau, F., Die Wachstumsverhiiltnisse von Boiviea volubilis Hkr. fil. Abhandl. d. 

 Naturw. Ver. z. Bremen. 6: 433. 



Fig. 40. Etiolated 

 culture of Arodes. 



