2 28 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



were found to be capable of twining around thin wooden rods sup- 

 ported in a vertical position. The action of the last-named species 

 is held by Noll to indicate a method by which the twining habit 

 might arise in any species with a pliant stem, in which torsions arise. 

 In connection with the aspect of the subject under discussion in the 

 present paper, this capacity for twining might be regarded as an in- 

 herited quality in the seedlings in question, and to be made possible 

 by the torsions characteristic of certain etiolated stems of seedlings. 

 So far as the evidence at hand is to be regarded as conclusive how- 

 ever, the power of twining is to be denied to fully etiolated adult stems ; 

 at least it may be said to be " not proven." It is by no means im- 

 probable however that it might be exhibited by seedlings and 

 young stems arising from tubers or propagative bodies of some 

 species. 



The attenuated stems of climbers offer some evidence upon the 

 effect of nutrition on development. The translocation of the necessary 

 supply of constructive material from a basal reservoir through the 

 long thin stems in which the cross section of the conducting tissues 

 is very small, must result in a sufficiency of supply reaching the 

 apical portion of the stem after a certain length has been reached. 

 This upward transportation of carbohydrates is also rendered more 

 difficult by the lack of development in the transpiratory organs. 

 Scarcely any doubt remains that the insufficient food supply does 

 operate to limit the stature of thin stems of all kinds, whether climb- 

 ing or not. 



The duration of the aerial etiolated shoots of climbers in some 

 instances such as in Apios^ Aristolochia and Menispermum, is fairly 

 comparable to that of the normal. The delicate physical structure 

 of etiolated stems makes the length of existence of organs grown in 

 darkness more or less dependent upon the mechanical treatment 

 which they receive from the experimenter. The lack of thickening 

 in the epidermal walls, and of the mechanical and vascular tissues in 

 general renders etiolated stems peculiarly liable to abrasions and 

 wounds which quickly result in death. If care was taken that the 

 action of air currents was excluded, and the etiolated organs were 

 not handled or bent sharply the length of life was greatly extended, 

 a fact also true of all etiolated organs, which in no instance were 

 found to exhibit the power of forming calluses or closing wounds in 

 an efficient manner unless brought into light. It is well known how- 



