﻿1 903] CURRENT LITER A TURE 7 5 



grown with success at Kew. In 1893 Dr. Scotland Miss Sarganf" published 

 a study of the pitchers of this plant, basing their observations on the Kew 

 material. Thistleton-Dyer adds a note ^^ based on teratological material, 

 "atavistic forms," as he designates them, which appeared after some ten 

 years cultivation. The pitchers are morphologically leaves, the inner surface 

 corresponding to the lower surface of the normal foliage leaf. The abnormal 

 forms represent a series of transitions from a normal leaf to the pitcher by 

 an increasing concavity of the under surface. The pitchers in the abnormal 

 material differ, however, from the fully developed organ in the open mouth, 

 uninflexed margins, and small size. Unless it be in one case, no indication 

 was found of any such transition stage having been observed in nature. The 

 production of pitchers is not a general characteristic of Dischidia, only a 

 small part of the whole number of species having this habit. He considers 

 that there can now be little doubt that the pitchers have as an ancestral form 

 leaves such as those of D, borneensis Beec, and D, collyris Wall., in which 

 the leaves are convex. He considers that the view of Treub, that the pitch- 

 ers are water- economizers, corresponds most nearly with the facts, and while 

 it is only in certain cases they collect rain water, under all circumstances they 

 serve to preserve water lost by transpiration. The whole root system of the 

 - plant is adventitious and the pitchers are provided with a copious root system 

 derived from one or more of a pair of aerial roots originating from the 

 petiole or the closely adjacent stem. There can be little doubt, he thinks, 

 that the roots utilize the humus contained in the pitchers as if it were ordi- 

 nary soil, and accepts the suggestion of Groom that the organic matter is 

 brought in by ants. He concludes, then, that there is in this plant a complex 

 adaptation in which the leaves, originally developed for the purpose of stor- 

 ing and economizing water, often imperfectly perform this function and are 

 then taken possession of by ants which supply solid in place of the liquid 

 nutriment. 



In Die Tropenpflanzen (6: 389. 1902) there is given a photograph 

 of a "double" Ananas from the Azores. ' Harshberger^^ has recently written 

 of the fasciation in the pineapple from Jamaica, where it seems to be not at 

 all uncommon. Usually the form assumed is fan-shaped, the component 

 fruits being arranged side by side, but sometimes one or more project, form- 

 ing an irregularly disposed row. The smallest example examined consisted 

 of two united fruits, while the largest, twenty inches across and twelve inches 

 high, was composed of a dozen or more. 



*' Annals of Botany 7:243-269. ph. 11-/2, 1893. 



^^'Thistleton-Dver, W. T., Morphological notes. VII. Evolution of pitchers 

 m Dischidia rafflesiana. Annals of Botany 16 : 365-369. pis. 14-^5- 1902. 



^^Harshberger, J. W., Coxcomh fasciation of pineapples. Proc. Acad, Sci- 

 Philad. 53 : 609-611. 1902. 



