88 DROSERA ROTTJNDIFOLIA. CHAP. VL 



appears to be to a certain extent antiseptic,, as it 

 checks the appearance of mould and infusoria, thus 

 preventing for a time the discoloration and decay of 

 such substances as the white of an egg, cheese, &c. 

 It therefore acts like the gastric juice of the higher 

 animals, which is known to arrest putrefaction by 

 destroying the microzymes. 



As I was anxious to learn what acid the secretion contained, 

 445 leaves were washed in distilled water, given nie by Prof. 

 Frankland; but the secretion is so viscid that it is scarcely 

 possible to scrape or wash off the whole. The conditions 

 were also unfavourable, as it was late in the year and the 

 leaves w'ere small. Prof. Frankland with great kindness under- 

 took to test the fluid thus collected. The leaves were excited 

 by clean particles of glass placed on them 24 hrs. previously. 

 No doubt much more acid would have been secreted had the 

 leaves been excited by animal matter, but this would have 

 rendered the analysis more difficult. Prof. Frankland informs 

 me that the fluid contained no trace of hydrochloric, sulphuric, 

 tartaric, oxalic, or formic acids. This having been ascertained, 

 the remainder of the fluid was evaporated nearly to dryness, and 

 acidified with sulphuric acid ; it then evolved volatile acid 

 vapour, which was condensed and digested with carbonate of 

 silver. " The weight of the silver salt thus produced was only 

 37 gr., much too small a quantity for the accurate determina- 

 tion of the molecular weight of the acid. The number obtained, 

 however, corresponded nearly with that of propionic acid ; and 

 I believe that this, or a mixture of acetic and butyric acids, were 

 present in the liquid. The acid doubtless belongs to the acetic 

 or fatty series." 



Prof. Frankland, as well as his assistant, observed (and this 

 is an important fact) that the fluid, " when acidified with sul- 

 phuric acid, emitted a powerful odour like that of pepsin." 

 The leaves from which the secretion had been washed were 

 also sent to Prof. Frankland; they were macerated for some 

 hours, then acidified with sulphuric acid and distilled, but no 

 acid passed, over. Therefore the acid which fresh leaves con- 

 tain, as shown by their discolouring litmus paper when crushed, 

 must be of a different nature from that present in the secretion. 

 Nor was any odour of pepsin emitted by them. 



