Fluid in the Ascidia o/" Nepenthes. 193 



covered in them some vegetable matter. Treviranus for instance 

 observed a tasteless water in the corolla of Maranta gibba, which 

 he however did not further examine; the same gentleman ex- 

 amined the watery secretion of Amomum Zerumbet, and caused 

 Dr. Goppert to subject it to chemical analysis, from which it re- 

 sulted that the fluid between the scales of the spikes consisted of 

 almost pure water, containing a small quantity of vegetable fibre 

 and mucus. 



The most remarkable instance of a watery secretion from the 

 leaves of plants is recorded in the ' Annals of Natural History ' 

 for 1848, in a paper by Mr. Williamson, who observed that the 

 leaves of Caladium destillatorium had the peculiar power of ex- 

 haling watery fluid from a point near the apex on the upper side. 

 Each full-grown healthy leaf, according to Mr. Williamson's ob- 

 servation, produced about half a pint of water during the night, 

 which, on being analysed, was found to contain a very minute 

 portion of vegetable matter. 



It appeared to me highly improbable that these fluid secre- 

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

 table matter, and no inoi'ganic substances whatsoever. If they are 

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

 to contain some of the salts which we find 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 I 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. 



Linnaeus regarded the ascidia oi 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 destillatoj'ia 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 



Phil. Mag. S. 3. Vol. 35. No, 235. Sept. 184-9. O 



