SOME FACTS ABOUT ABUMS. 
303 
Now tlie arum family are not deficient in these customary 
attractions, but they seem to try and outbid their neighbours 
by adding warmth to the list. Most arums, in the temperate 
zones at least, blossom early in the year, when the nights are 
still so chilly that a comfortable well-warmed bed is by no 
means to be despised ; and accordingly the common Italian 
arum is visited by all sorts of small flies, gnats, and midges, 
bringing with them in payment for their night’s lodging a 
tribute of pollen from their last quarters. 
Many South European and foreign arums are flesh- 
coloured or reddish brown, and emit such a carrion-like 
odour that the flesh-flies are attracted and so far deceived 
as to lay their eggs on them. In these species the lower part 
of the sheath, which is enlarged like a bulb, is shut off from 
the upper part hy a ring of longisli hairs which slope down¬ 
wards, and thus, while affording easy entrance to the warm 
chamber below, make the leaving of it again an impossibility. 
In return for bringing pollen to the pistil-flowers, the 
flies are caught and kept prisoners ; but not for long—only, in 
fact, until the anthers or pouches of the stamen-flowers above 
have burst and scattered their pollen, part of which naturally 
falls upon the captives, while part is brushed off* by them 
when they are let out. For as soon as they have fulfilled 
their object, the hairs at once wither away and the insects 
come out to carry the pollen to other blossoms, quite 
undeterred by the fact of their imprisonment, for the prison 
is in truth a most luxurious one, well warmed and scented; 
besides, they have been fed with nectar from the faded pistil- 
flowers. The hairy arum of the South is, however, said to 
express her gratitude to her pollen-bringing visitors by 
keeping and devouring the greater number, which are sucked 
and digested by the acid juice exuding from the hairs with 
which her sheath is lined. 
But there are other guests for which a number of the 
aroids seem especially to prepare their warm lodgings ; these 
are the little marsh snails, which climb up the stalk and find 
entrance into the enlarged part of the sheath by a narrow 
aperture at its base, which closes later on. Aroids all like a 
damp situation, and growing as they do in shady woods, on 
river banks, and in marshes, no creatures could be better 
adapted for rendering them the services they need than snails, 
whose tastes in this respect are so very similar to their own. 
Most of those observed by Delpino were visited by small 
snails, and we may reasonably suppose that the foreign 
varieties are equally attractive to the race in their own 
lands. 
