(14) Square bits of the leaves of spinach, cabbage, and a saxifrage,
and the entire leaves of Erica tetralix, all excited the glands to
increased secretion. The spinach was the most effective, for it caused
the secretion evidently to increase in 1 hr. 40 m., and ultimately to
run some way down the leaf; but the glands soon began to dry, viz.
after 35 hrs. The leaves of Erica tetralix began to act in 7 hrs. 30
m., but never caused much secretion; nor did the bits of leaf of the
saxifrage, though in this case the glands continued to secrete for
seven days. Some leaves of Pinguicula were sent me from North Wales, to
which leaves of Erica tetralixand of an unknown plant adhered; and the
glands in contact with them had their contents plainly aggregated, as
if they had been in contact with insects; whilst the other glands on
the same leaves contained only clear homogeneous fluid.
(15) Seeds.—A considerable number of seeds or fruits selected by
hazard, some fresh and some a year old, some soaked for a short time in
water and some not soaked, were tried. The ten following kinds, namely
cabbage, radish, Anemone nemorosa, Rumex acetosa, Carex sylvatica,
mustard, turnip, cress, Ranunculus acris, and Avena pubescens, all
excited much secretion, which was in several cases tested and found
always acid. The five first-named seeds excited the glands more than
the others. The secretion was seldom copious until about 24 hrs. had
elapsed, no doubt owing to the coats of the seeds not being easily
permeable. Nevertheless, cabbage seeds excited some secretion in 4 hrs.
30 m.; and this increased so much in 18 hrs. as to run down the leaves.
The seeds or properly the fruits of Carex are much oftener found
adhering to leaves in a state of nature than those of any other genus;
and the fruits of Carex sylvatica excited so much secretion that in 15
hrs. it ran into the incurved edges; but the glands ceased to secrete
after 40 hrs. On the other hand, the glands on which the seeds of the
Rumex and Avena rested continued to secrete for nine days.
Public-domain text, read in full here on John Shaqi.
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