230 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



in the " partial" etiolations made by him, and Von Mohl previously 

 reported that the tendrils of etiolated plants of Br\onia were capable 

 of a normal exercise of their functions in darkness.'"'' 



Growth and Development of Seedlings in Darkness. — Seedlings 

 present more than one physiological type, and it will be profitable 

 to divide them into several groups for the purposes of the present 

 discussion. The species included in the present series of experi- 

 ments \x\c\\xd.^ AEsciihcs hippocastantuu (p. igi) , Artsaema Dracon- 

 liuin (p. 48), A. triphylluin (p. 50), Castanca deniata (p. 91), Cocos 

 micifera (p. 95), Coix Lachryma-Jobi {p. 97), Hicoria minivia (p. 

 114), H. ovata (p. 115), and H. sp. (p. 113), Glcditsia triacanthos 

 (p. 113), Phaseohis sp. (p. 147), ^lercus paliistris (p. 158), ^. 

 rubra (p. 159), and .^. sp. (p. 161), and Ricinns conwiiiuis (p. 169). 



Of the above species Arisacma, Cocos, Coix, Ricinns, as well as 

 Zca, have a comparatively large quantity of reserve material stored 

 in an endosperm, which in all instances except in Ricinns remains 

 buried in the substratum until a certain amount of food material is 

 withdrawn, and then the storage organ perishes. The degree of 

 development and duration achieved by the seedling in such instances 

 is dependent upon the amount of reserve food available in the seed, 

 and the efficiency of its protection from decay and the attacks of fungi 

 and bacteria. Thus in Coix the amount of material stored in the seed 

 is not greater than in Zca, but the etiolated plantlets of the former 

 attained a height much greater than the latter, in which but a frac- 

 tional part of the starch and other material was absorbed by the 

 seedling. Decay usually sets in early in the germination of 

 the grain and the growth of etiolated seedlings of Zea soon 

 ceases because of lack of food material. Cocos may be offered as 

 an example of a device by which a comparatively enormous amount 

 of food is stored up and protected from damage from external causes, 

 nearly all of it being available to the developing plantlet. A seed- 

 ling of this plant lived in the dark room for fifteen months saprophyt- 

 ically at the expense of the endosperm, and when examined at the 

 close of this period had not used more than half of the total amount 

 of the endosperm. During the interval, seven large leaves had been 

 developed and an amount of growth carried on fully equal to the 



"•^ Sachs. Wirkung des Lichts auf die Bliithenbildung unter Vermittlung der 

 Laubblatter. Bot. Zeitung, 23 : 119. 1865. 



Von Mohl. Ueber den Bau und das Winden der Ranken und Schlingpflanzen. 

 pp. S3, 84 and 122. 127. 1S27. 



