Cuar. XVI.] MOVEMENTS OF THE LEAVES. 299 
nine different kinds, which could not be recognised, excepting one of 
Ranunculus, and several belonging to three or four distinct species of 
Carex. It appears that fewer insects are caught late in the year than 
earlier; thus in Cumberland from twenty to twenty-four insects were 
observed in the middle of July on several leaves, whereas in the 
beginning of September the average number was only 2°27. Most of 
the insects, in all the foregoing cases, were Diptera, but with many 
minute Hymenoptera, including some ants, a few small Coleoptera, 
larvee, spiders, and even small moths. 
We thus see that numerous insects and other objects are 
caught by the viscid leaves ; but we have no right to infer 
from this fact that the habit is beneficial to the plant, any 
more than in the before-given case of the Mirabilis, or of 
the horse-chestnut. But it will presently be seen that dead 
insects and other nitrogenous bodies excite the glands to 
increased secretion; and that the secretion then becomes 
acid and has the power of digesting animal substances, such 
as albumen, fibrin, &c. Moreover, the dissolved nitrogenous 
matter is absorbed by the glands, as shown by their limpid 
contents being aggregated into slowly moving granular 
masses of protoplasm. The same results follow when insects 
are naturally captured, and as the plant lives in poor soil 
and has small roots, there can be no doubt that it profits by 
its power of digesting and absorbing matter from the prey 
which it habitually captures in such large numbers. It will, 
however, be convenient first to describe the movements of 
the leaves. 
Movements of the Leaves.—That such thick, large leaves as 
those of Pinguicula vulgaris should have the power of curving 
inwards when excited has never even been suspected. It is 
necessary to select for experiment leaves with their glands 
secreting freely, and which have been prevented from cap- 
turing many insects; as old leaves, at least those growing 
in a state of nature, have their margins already curled so 
much inwards that they exhibit little power of movement, 
or move very slowly. I will first give in detail the more 
important experiments which were tried, and then make 
some concluding remarks, 
Experiment 1.—A young and almost upright leaf was selected, with 
its two lateral edges equally and very slightly incurved. A row of 
small flies was placed along one margin. When looked at next day, 
after 15 hrs., this margin, but not the other, was found folded inwards, 
