80 DROSERA ROTUNDIFOLIA. Cuar. V 
on with other substances, and it was found to act most enor- 
getically, but as no exact account of these trials was kept, they 
are not here introduced. 
Mucus —Thick and thin mucus from the bronchial tubes, 
placed on three leaves, caused inflection. A leaf with thin 
mucus had its marginal tentacles and blade somewhat curved 
inward in 6 hrs. 80 m., and greatly so in 20 hrs. ‘he action of 
this fluid no doubt is due either to the saliva or to some albu- 
minous matter* mingled with it, and not, as we shall see in the 
next chapter, to mucin or the chemical principle of mucus. 
Saliva.—Human saliva, when evaporated, yicldst from 1:14 to 
1:19 per cent. of residue; and this yields 0°25 per cent. of ashes, 
so that the proportion of nitrogenous matter which saliva con- 
tains must be small. Nevertheless, drops placed on the discs of 
eight leaves acted on them all. In one case all the exterior ten- 
tacles, excepting nine, were inflected in19 hrs. 30 m.; in another 
ease a few became so in 2 hrs., and after 7 hrs. 30 m. all those 
situated near where the drop lay, as well as the blade, were 
acted on. Since making these trials, I have many scores of 
times just touched glands with the handle of my scalpel wetted 
with saliva, to ascertain whether a leaf was in an active condi- 
tion; for this was shown in the course of a few minutes by the 
bending inwards of the tentacles. The edible nest of the Chinese 
swallow is formed of matter secreted by the salivary glands; two 
grains were added to one ounce of distilled water (one part to 218), 
which was boiled for several minutes, but did not dissolve the 
whole. The usual-sized drops were placed on three leaves, and 
these in 1 hr. 30 m. were well, and in 2 brs. 15 m. closely, 
inflected. 
Isinglass.—Drops of a solution about as thick as milk, and of 
a still thicker solution, were placed on eight leaves, and the ten- 
tacles of all became inflected. In one case the exterior tentacles 
were well curved in after 6 hrs. 30 m., and the blade of the leaf 
to a partial extent after 24 hrs. As saliva acted so efficiently, 
and yet contains so small a proportion of nitrogenous matter, I 
tried how small a quantity of isinglass would act. One part was 
dissolved in 218 parts of distilled water, and drops were placed 
on four leaves. After 5 hrs. two of these were considerably and 
two moderately inflected; after 22 hrs. the former were greatly 
and the latter much more inflected. In the course of 48 hrs. 
* Mucus from the air-passages to contain some albumen. 
is said in Marshall, ‘Outlines of + Miiller’s ‘ Elements of Physio 
Physiology,’ vol. ii. 1867, p. 364, logy,’ Eng. Trans. vol. i. p. 514. 
