MEMOIRS OF THE NEW YORK BOTANICAI. GARDEN. 239 



Etiolation of Stems of Woody Perennials. — Species with woody 

 stems which were grown in darkness in my experiments include Ace7- 

 rubruni (p. i88), Bacchan's haliinifolia (p. 80), Cornus aliej'nifolia 

 (p. g*]), jFagns Americana {p^. 105, 194), Populus Simo7ui {p. 154)* 

 ^lercus sp. (p. 161), and Rhus sp. (p. 169) in the adult stage, and 

 Castanca dc}itata{j). 91), AEsctilus hippocastajiiuii {p. 191), Gleditsia 

 triacanthos (p. 113), Hicoria minhna {^. 11^), H. ovata (p. 115), 

 H. sp. (p. 113), ^lerctcs -pahistris (p. 158), J^. rubra (p. 159) and 

 J^. sp. (p. 161), in the seedling, or juvenile stage. The reactions 

 showed the greatest divergence, a part of which may be attributed 

 to the unsuitability of the cultural conditions offered for some 

 of the forms. Effects from such causes were recognizable to some 

 extent, and results due to unfavorable factors may be easily elimi- 

 nated in the analysis of the influence of darkness upon the growth 

 and development of the species in question, I^^agus Americana, as 

 examined by myself, and I^. sylvatica according to Jost bear a 

 specialized relation lo light and darkness of an unmistakable char- 

 acter. The buds of young plants might awaken in darkness in my 

 own tests, but the buds of adult plants a few years older did not 

 begin activity except under the influence of light. This influence 

 was furthermore wholly of a stimulative character, as Jost found that 

 when a few buds of a confined plant were exposed to light the stimu- 

 lation resulting was sufficient to awaken others on distant parts of 

 the shoot from which light \vas excluded, a result w'rongly attributed 

 by Jost to the necessity for the action of light in the construction of 

 formative substances necessary for the development of buds. Further- 

 more, this reaction illustrates most strikingly the difference of results 

 that may be obtained by total and partial etiolations. Again, this 

 awakening of the buds only under the influence of light, and the fact 

 that etiolated stems do not make greater growth than the normal, 

 points most strongly to the conclusion that, in these two species at 

 least, light does not exert a retarding, or indeed a direct action of 

 any kind upon grow^th ; the behavior of the plant with regard to 

 this factor being wholly in response to its stimulative action. 



A further phenomenon of marked interest in Fagiis was the fact 

 that both young and adult plants formed calluses rapidly in darkness, 

 and that the buds arising from these calluses made a much more 

 rapid growth than the normal, being capable of extension in dark- 

 ness as well as in light. The typical buds showed only a slight 



