NOTES.—ORIGINAL AND SELECTED. 287
his journey." For, in addition to the utter indifference of birds
to passing trains, their general preference of embankments to
cuttings must tend in itself very decidedly to prevent them from
being seen by travellers.
BOTANY.
Extra-floral Nectaries of Vetches.—An interesting
feature of the Spring Ramble of the Club, which took place on
May 22nd, was the observation of ants feeding on honey
exuding from the stipular nectaries of the Vetches, Vicia sepium
and V. sativa. The writer was interested in the subject some
years ago, and notes were taken of the observations made. As
the editor of the Essex Naturalist thinks that these may be of
interest to others, they are briefly summarised below.
It was noticed that on bright, sunny days, ants were busily
feeding on the nectar in shallow, pigmented pits on the under-
surface of the stipules of the Vetches mentioned above. A
visit to Kew Gardens in June, 1902, gave opportunities for
observing 21 species of Vicia (British and foreign). It was found
that, wherever the small pigmented pits occurred on the under-
side of the stipules, nectar was exuded and ants were feeding.
In cases where there were no pigmented depressions, both the
nectar and the ants were absent. Of the 21 species examined, 9
possessed stipular nectaries, amongst them being the British
species V. lutea, sepium, sativa, and the cultivated Bean (V. faba).
Four British species were examined, which possessed neither
nectaries nor pigmented pits, viz., V. cracca, bithynica, sylvatica
and V. orobus.
It seemed probable that the presence of the ants might be
useful to the plants in protecting them from the ravages of
caterpillars, etc. In June of 1906 the writer tried a simple
experiment on a plant of V. sepium where ants were feeding. A
small caterpillar was placed on a leaf, and it began to crawl
down the stem, but on meeting the ants it was attacked by them
and quickly slipped off the leaf by means of its own thread. The
experiment was repeated several times with the same result.
The ants did not leave the nectar in order to attack the cater-
pillar, but merely bit at it when it came near them. Any creeping
insect coming up the stem would have to pass a pair of stipules
where ants might be feeding. On the other hand, the presence