88 DROSERA ROTUNDIFOLIA. Cuar. 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 me 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 were 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 sulphurie 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 aciditied 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. 
