128 Dr. A. Voelcker on the Chemical Composition of the 



sembryanthema ; and I found it subsequently at a distant point 

 of False Bay, near u the Strand/' and again at Hout Bay. In all 

 these places it was found among plants and bushes growing on 

 sandy dunes near the sea. 



July 13, 1849. 



XVI. — On the Chemical Composition of the Fluid in the Ascidia of 

 Nepenthes. By Dr. A. Voelcker of Frankfort*. 



The watery secretions of certain plants belonging to the genera 

 Nepenthes, Cephalotus, and Sarracenia, have long attracted the 

 attention of botanists ; but whilst the secreting organs of these 

 plants have been minutely described, the chemical nature of the 

 fluid itself has been but very imperfectly examined. That these 

 liquids have not met with the attention to which their importance 

 entitles them, may be accounted for by the circumstance that few 

 chemists have an opportunity of obtaining the unaltered fluids, 

 and that even those who are fortunate enough to procure them, 

 seldom can command a sufficient quantity to enable them to inves- 

 tigate their nature. With the exception of Dr. Turner's analysis 

 of the fluid in the ascidia of Nepenthes, I know of no other ana- 

 lysis of this fluid or of similar secretions. The botanists who 

 have given attention to the subject of the watery secretions of 

 the leaves of plants have found these secretions to consist in most 

 cases of nothing but pure water, and have only occasionally dis- 

 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. 



* Read before the Botanical Society of Edinburgh, July 12, 1849. 



