INSECT AGENCY ON THE DISTRIBUTION OF PLANTS. 269 
points out a very interesting subject for investigation, and I trust 
that the readers of the Journal will not lose sight of it. 
If Sphinx Convolvuli is the chief agent in the fertilization of 
Convolvulus sepium, then the reason why that plant seldom in 
Britain perfects seed (as is said to be the case) is readily explained. 
he moth is rare in Britain, and I do not at present remember any 
record of its having been seen visiting the flowers of Convolvulus, 
though it is generally taken in the act of hovering over flowers, 
notably Petunia and honeysuckle. Though Sphina Convolvuli oc- 
curs throughout Britain (even beyond the range of Convolvulus, e.g. 
Orkney), yet it is most especially a southern insect, and perhaps 
that may account in some measure for the rarity in a wild state 
(at least in my experience) of Convolvulus sepium in Scotland. 
Dianthecia (a genus of night-flying moths) must exert a great 
influence upon the fertilization (and consequent abundance) of 
Silene and Lychnis. In fact, the perpetuation of the race of these 
moths depends upon the fertilization of the plants, since the larvee 
feed only upon the unripe seeds. This is a case somewhat similar 
to, though by no means so extraordinary as, that mentioned by 
Professor Riley at the last meeting of the American Association 
for the Advancement of Science. Professor Riley showed how the 
fertilization of Yucca depended on the agency of a moth, the 
female of which collects the pollen and places it on the stigma, for 
the express purpose that the larvae, produced from the eggs which 
she deposits on the ovary of the plant, may have a supply of un- 
ripe seeds to feed upon. In regard to Lychnis and Silene, it is 
possible that if there were no Dianthecic the plants might be more 
numerous, since other moths visit the flowers, though the Dian- 
theeciee are the chief visitors. Silene maritima is the most fre- 
quented species (it is, perhaps, worth remarking that it has also 
the largest flowers, and is, perhaps, the most numerous in indi- 
viduals) of course, in proportion to its restricted usually maritime 
habitat; Lychnis Flos-cuculi is more especially visited by Dian- 
thæcia Cucubali; and Silene Otites a plant of the eastern counties, 
by Dianthecia irregularis. On the Continent this insect frequents 
: Gypsophila paniculata. I know of no insect visitors to Silene 
acaulis and Lychnis alpestris. Possibly, if Lychnis alpestris had 
-more insect visifors, it might be more abundant on our mountains, 
though the peculiarities of the locality (in Forfarshire, at least) 
have doubtless something to do with its restricted range. 
