196 DROSERA ROTUNDIFOLIA. Crap. VILL 
an immersion of 8 hrs. 20 m. the leaves were washed and placed 
in water; next morning, after about 16 hrs., they were still 
inflected and discoloured; on the succeeding day they were 
evidently dead. Two leaves were immersed in a stronger 
mixture, of one part to fifty of water; in 1 hr. 15 m. the glands 
became as white as porcelain, as if they had been dipped in boil- 
ing water; very few of the tentacles were inflected; but after 
4 hrs. almost all were inflected. These leaves were then placed 
in water, and next morning were evidently dead. Half-minim 
drops of the same strength (viz. one part to fifty of water) were 
next placed on the discs of five leaves; after 21 hrs. all the 
outer tentacles were inflected, and the leaves appeared much 
injured. I likewise touched the secretion round a large number 
of glands with minute drops (about =, of a minim, or ‘00296 ml.) 
of Scheele’s mixture (6 per cent.); the glands first became bright 
red, and after 3 hrs. 15 m. about two-thirds of the tentacles 
bearing these glands were inflected, and remained so for the two 
succeeding days, when they appeared dead. 
Concluding Remarks on the Action of Acids.—It is 
evident that acids have a strong tendency to cause the 
inflection of the tentacles ;* for out of the twenty-four 
acids tried, nineteen thus acted, either rapidly and 
energetically, or slowly and slightly. This fact is 
remarkable, as the juices of many plants contain more 
acid, judging by the taste, than the solutions employed 
in my experiments. From the powerful effects of so 
many acids on Drosera, we are led to infer that those 
naturally contained in the tissues of this plant, as well 
as of others, must play some important part in their 
economy. Of the five cases in which acids did not 
cause the tentacles to be inflected, one is doubtful; 
for uric acid did act slightly, and caused a copious 
secretion of mucus. Mere sourness to the taste is no 
* According to M. Fournier  Berberis instantly to close; though 
(‘De la Fécondation dans les drops of water have no such power, 
Phanérogames.’ 1863, p. 61) drops _— which latter statement I can com 
of acetic, hydrocyanic, and sul- firm. 
phuric acid caye the stamens of 
