Fluid in the Ascidia 0/ Nepenthes. 129 



It appeared to me highly improbable that these fluid secre- 

 tions should consist of pure water with merely a trace of vege- 

 table matter, and no inorganic substances whatsoever. If they are 

 to be regarded as true secretions, we naturally should expect them 

 to contain some of the salts which we tind in all juices of plants. 

 I was therefore anxious to examine this point, and I am glad that I 

 have an opportunity of bringing the results of my analysis of the 

 fluid in the ascidia of Nepenthes before the notice of the Bota- 

 nical Society. It is through the kindness of Prof. Balfour, 

 Mr. Evans of the Experimental Gardens, Messrs. Jas. Dickson and 

 Sons, and Sir W. Hooker, that I have obtained the materials for 

 the following analysis, and 1 consider it my duty to express here 

 publicly my deep sense of gratitude for the kindness and libe- 

 rality with which the above-named gentlemen have assisted me 

 in carrying on this inquiry. I have also to express my obliga- 

 tions to Dr. George Wilson for kindly allowing me the use of 

 his laboratory. 



Linnseus regarded the ascidia of Nepenthes as a natural reser- 

 voir for rain, and thought that the water found in them was intro- 

 duced from without, and was not secreted by the plant itself. 

 His opinion however has been contradicted already by many bo- 

 tanists, especially Treviranus, who observed that the water in the 

 pitchers of Nepenthes destillatoria is always clear, and that there 

 exists a distinct secreting apparatus. Treviranus says, in an ar- 

 ticle which appeared in the ^ Edinb. New Philosoph. Journal^ for 

 Oct. 1832— April 1833 :— " The parietes of the leaf of Nepenthes 

 destillatoria are traversed by a multitude of proportionally large 

 anastomosing veins, which contain many true spiral vessels. The 

 upper half of its inner surface is covered with a blue rind, as parts 

 often are which require to be protected from the action of water ; 

 the under half is, on the contrary, shining and full of gland-like 

 eminences directed downwards, and having a hole almost visible 

 to the naked eye, which is uncovered by the cuticle which the 

 remainder possesses." The watery secretion reaches generally 

 to the level of these glands in the middle of the ascidium, and he 

 thinks that they are true secreting organs. This peculiar struc- 

 ture alone gives a strong reason for thinking that the water in 

 the ascidia of Nepenthes is supplied by the plant itself, and the 

 circumstance that water is found in pitchers which have never 

 been opened is another argument against the supposition that it 

 comes from without. The subjoined analysis of the fluid more- 

 over leaves no doubt that it is a true secretion. 



Before I enter into the particulars of my experiments I will 

 mention that I could not detect any oxalic acid in the fluid of 

 Nepenthes. It is stated in Lindley's ^ Vegetable Kingdom ' that 

 Dr. Turner found this acid in combination with potash, and that 

 Ann. ^ Mag. N. Hist. Ser. 2. Vol.'w. 9 



