Royal Society. 415 
so abundant as to destroy thousands of cattle; and many were 
subsequently found whose bodies exhibited one mass of scorched 
flesh. 
Within the Bay of Fonseca, and two miles from the volcano, it is 
stated that two islands, from two to three hundred yards in diameter, 
were thrown up, probably from the deposit of masses of scoriz on 
previously existing shoals. 
Jan. 14.—Dr. Daubeny’s paper entitled, “ On the action of Light 
upon Plants, and of Plants upon the Atmosphere,” was resumed and 
concluded. 
The objects of the experimental inquiries of which the author gives 
an account in this paper were, in the first place, to ascertain the ex- 
tent of the influence of solar light in causing the leaves of plants to 
emit oxygen gas, and to decompose carbonic acid, when the plants 
were either immersed in water, or surrounded by atmospheric air. 
The plants subjected to the former mode of trial were Brassica 
oleracea, Salicornia herbacea, Fucus digitatus, Tussilago hybrida, Co- 
chlearia armorica, Mentha viridis, Rheum rhaponticum, Allium ur- 
sinum, and several species of Graminee. Geraniums were the only 
plants subjected to experiment while surrounded with atmospheric 
air. Comparative trials were made of the action on these plants of 
various kinds of coloured light, transmitted through tinted glass, of 
which the relative calorific, illuminating, and chemical powers had 
been previously ascertained ; and the results of all the experiments 
are recorded in tables; but no general conclusion is deduced from 
them by the author. He next describes a few experiments which 
he made on beans, with a view to ascertain the influence of light on 
the secretion of the green matter of the leaves, or rather to deter- 
mine whether the change of colour in the chromule is to be ascribed 
to this agent. The third object of his inquiries was the source of 
the irritability of the Mimosa pudica, from which it appeared that 
light of a certain intensity is necessary for the maintenance of the 
healthy functions of this plant, and that when subjected to the ac- 
tion of the less luminous rays, notwithstanding their chemical influ- 
ence, the plant lost its irritability quite as soon as when light was 
altogether excluded. He then examines the action of light in causing 
exhalation of moisture from the leaves; selecting Dahlias, Helian- 
thuses, Tree Mallows, &c., as the subjects of experiment. The 
general tendency of the results obtained in this series is to show that 
the exhalation is, ceteris paribus, most abundant in proportion to the 
intensity of the light received by the plant. He also made various 
comparative trials of the quantity of water absorbed, under dif- 
ferent circumstances, by the roots of plants, and chiefly of the He- 
lianthus annuus, Sagittaria sagittifolia, and the Vine. From the ge- 
neral tenor of the results of these and the preceding experiments, he 
isinclined to infer that both the exhalation and the absorption of 
moisture in plants, as far as they depend on the influence of light, 
are affected in the greatest degree by the most luminous rays ; that 
all the functions of the vegetable economy which are owing to the 
presence of this agent, follow, in this respect, the same law; and 
that in the vegetable, as well as in the animal kingdom, light acts in 
