NOTES ON RECENT RESEARCH. 



705 



pointed out the improbability at first sight of any addition to our know- 

 ledge of the morphology of the pitchers, in consequence of the exhaustive 

 monograph by Dr. Scott and Miss Sargent (Ann. Bot. 1893, 243-262, 

 tt. xi. xii.), the author writes : " It is, however, one of the results of the 

 change of conditions effected by cultivation to rouse latent tendencies 

 and to develop atavistic forms which are often extremely instructive. 

 Such deviations from specific stability are usually the result of seminal 

 reproduction. In the case I am about to describe it is purely vegetative, 

 and therefore of even greater theoretical interest. The structure of the 

 pitcher in Dischidia Bafflesiana is well known. ... As demonstrated 

 by Treub, it is 'a modified leaf in which the inner surface corresponds 

 to the lower surface of the normal foliage leaf . . . and it is important to 

 observe that normally the form of the future pitcher is, as it were, laid 

 down from the first, and there is no indication of any passage from the 

 form of the normal foliar leaf to that of the pitcher. Such intermediate 

 stages have, however, made their appearance after some ten years' cultiva- 

 tion of the Kew plants. . . . These indicate a complete transition from 

 the ordinary leaf by an increasing concavity of its under surface to a 

 pitcher, which, however, still differs, in its open mouth, uninflexed margins, 

 and small size, from the fully-developed organ. It can hardly be doubted 

 that these indicate the path by which the latter has been arrived at from 

 the ordinary leaf." The author points out that " the production of pitchers 

 is only characteristic of a small part of the genus. From this the inference 

 may be fairly drawn that the property of producing pitchers is rather an 

 individual adaptation than bound up with a particular generic type, as it 

 is apparently in Sarracenia and Nepenthes." Discussing the teleological 

 object attained by the plant in forming these pitchers, and referring to 

 the views of Carpenter, Beccari, and Delpino, the author says : " Treub's 

 view that the pitchers are water-economisers appears most nearly to 

 correspond with the facts. As he points out, it is only in certain, and by 

 no means inevitable, positions that the pitchers collect rain-water. I can 

 only conclude that on the average they pay. But under all circumstances 

 they serve to preserve water lost by transpiration, which is one of the 

 severest taxes the plant has to meet. As is well known, the pitchers of 

 Dischidia Bafflesiana contain a copious root system. This is derived 

 from one or more of a pair of aerial roots, which are either derived from 

 the petiole or from the stem in close adjacence. The whole root system 

 of the plant is adventitious. And I venture to hazard the theory that, in 

 so far as adventitious roots are not merely organs of support, their pro- 

 duction is in response to the demand for water. In plate xv. fig. 1, it will 

 be noticed that each petiolar root is applied to the concavity of its corre- 

 sponding leaf, and in fig. 3 it will be seen that as soon as the concavity 

 becomes a pitcher the roots are included within it. The whole, if I may 

 say so, evolutionary data tend to prove then that the primary object of 

 the pitchers is the supply or, at any rate, economy of water. But the 

 copious development of the enclosed root system, which is often matted 

 with organic debris, seems to go beyond this. The researches of Groom 

 {Ann. Bot. 1893, 223, 242), I think, leave no doubt that the roots utilise 

 this as if it were ordinary soil (I. c. 227). From whence is the organic 

 matter derived ? There can be no doubt that, except when in the erect 



