Medical Officers of the Army of India.

61

to collect birds' eggs. The presence of shelter-huts on the island indicates
that these visits are of some duration, and altogether the conditions necessary
to explain the presence of these three weeds without having recourse to the
hypothesis of ocean-dispersal are abundantly fulfilled.

     The grasses too suggest at once the possibility of wind-distribution. But
none of those in the list are adapted (as an Imperata or a Saccharum would be)
for this method of distribution. Some species of Panicum have been supposed
to be distributed by the sea, but the Oplismenus and the Setaria, whose general
resemblance to the Panica suggests for them this possibility, are most distinctly
not coast plants on the mainland, and the hypothesis can hardly be applied to
them. The Apluda and the Andropogon are, however, both coast and inland
plants; for them therefore, though it is by no means probable, a sea-dispersal is
just possible. Then any, or all, of them may conceivably have been distributed by
marsh birds if their grains had happened to fall on the mud where these birds
were wading. But it is far more probable that all the grasses mentioned here
are, as Eleusine œgyptiaca certainly is, to be accounted for in the Laccadives as
weeds of cultivation.

     Man then has almost certainly either intentionally or unintentionally intro-
duced 43 species, or 54 per cent., of Laccadive flora. At the same time it is
possible that he may have introduced as many as 63 species, or 78¾ per cent.
of the whole, while the probability is that man has introduced 56 species, or 70
per cent. of the whole flora. Conversely, the number of species that may have
been introduced otherwise than by human agency is 37, or 46 per cent, of the
flora; on the other hand, the number of species whose introduction has almost
certainly been independent of man's agency is only 17, making 21¼ per cent. of
the flora; the number of species whose appearance is probably independent of
man is 24, or 30 per cent. of the flora.

     Of the 17 species that have almost certainly not been introduced by man
the following five are inland plants:—

Vitis carnosa.

Herpestis Monniera.

Oldenlandia diffusa.

Nephrodium molle.

Nephrolepis tuberosa.

     The introduction of Vitis carnosa is almost certainly due to the agency of
frugivorous birds, which have eaten its fruits on the mainland and deposited the
undigested seeds on the island where it occurs. Still it has to be remembered
that fruits belonging to this natural order have been found in ocean-drifts,¹
and that seeds of species whose fruits have been cast up by the sea have sub-
sequently germinated.²Besides the wild vine, frugivorous birds, as has already
been said, may have introduced Premna; but, whereas for the vine the probabi-

          ¹Hemsley: "Challenger " Reports; Botany, vol. i, part iii, p. 290.

          ²Lefroy: Bot. Bermuda, p. 61.