ID* Dr. A. Voelcker on the Chemical Composition of the 



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 

 he also detected a trace of organic matter, which caused the 

 watery fluid when boiling to emit an odour of boiled apples. 

 Though I have examined the water of many pitchers from four 

 different localities, and paid particular attention to the detection 

 of oxalic acid, I have failed in finding a trace of it, and I am 

 therefore inclined to believe that Dr. Turner, on account of the 

 minute quantity of solid matter which he must have got on eva- 

 poration of the water, was unabk to subject the minute crystals 

 which he took for superoxalate of potash to a further examina- 

 tion, which would have shown him that the crystals were not 

 superoxalate of potash, but chloride of potassium. The propor- 

 tion of chloride of potassium which I found in the fluid is consider- 

 able ; it is deposited from the liquid after evaporation in the form 

 of minute but very regular cubes. The odour of boiled apples 

 which Dr. Turner observed I found very distinct when the water 

 was heated to the boiling-point. Besides chloride of potassium I 

 found malic and a little citric acid, in combination usually with 

 soda, lime and magnesia, and a small quantity of another orga- 

 nic matter which gave a yellow tint to the water during its eva- 

 poration. The quantity of the latter was too minute to enable 

 me to ascertain its chemical nature. 



I will now proceed to describe the experiments with the dif- 

 ferent fluids in the ascidia of Nepenthes : — 



1 . Fluid from an unopened pitcher-plant grown in the Bota- 

 nical Garden, Edinburgh. 



The water which I got on the 12th of June, 1849, was per- 

 fectly colourless and clear ; it had an agreeable, not very pro- 

 nounced smell and a refreshing taste. Though its taste was not 

 sour, litmus paper showed the presence of an acid or an acid salt 



