224 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



Cotyledonary stalks of twining plants are excessively elongated 

 in darkness in species in which the cotyledons are raised above the 

 soil, but in others in which the cotyledons remain below the surface 

 naturally, the first internode of the plumule takes up this action, and 

 in some instances as in Hicoria (pp. 113-117), AEsciihis (p. 191) and 

 others in my own observations, the increase is shared by all of the suc- 

 ceeding internodes. This action is not confined to the climbing plants. 



Alterations in the rate of growth and final length due to etiola- 

 tion are variously distributed in climbing stems. The basal inter- 

 nodes of Apios show the greatest increase in length over the normal, 

 while the median members are but little changed. The basal por- 

 tion of the aerial stem of Boiviea, which is morphologically to be 

 considered as an inflorescence axis is greatly elongated while the 

 terminal braching portion is much dwarfed. The median inter- 

 nodes of Bryonia appear to exhibit a tendency to excessive elonga- 

 tion according to Sachs, the basal ones not reaching the normal size. 

 The basal internodes of Falcata w^ere elongated more excessively 

 than the other portions of the stem, although all of the internodes 

 were doubled in length. Mcnisfcrmum did not develop internodes 

 in any instance equal to the normal average, and the limited growth 

 of this species in darkness, w^hether directly due to limited nutrition 

 or not, yet is certainly conditioned by it, since the amount of reserve 

 material in the slender rhizomes is very small. In Phaseolus, as 

 tested in " partial " etiolations by Sachs the terminal internodes were 

 much more elongated than the basal ones in darkness. It is to be 

 seen, therefore, that the influence of darkness on climbing (twining) 

 stems causes local disturbances of the rate of growth, and altera- 

 tions in the location of the zone of maximum elongation. 



Ibervillea is a tendril climber and the stems reached but a frac- 

 tion of their normal length in darkness, the etiolated internodes being 

 about normal length however. Smilax, which is also a tendril 

 climber, sent up long shoots which were much less than the normal 

 length. Extensive observations are not at hand, yet it is believed 

 that multiplication of the internodes in darkness does not occur 

 among twining plants, the reaction consisting wholly so far as length 

 is concerned, in alterations in the length of internodes, which may 

 not be equal to the normal in number. 



Etiolated stems of climbing plants were prophototropic so far 

 as my own observations go, and the capacity for the reaction to 



