344 The Romance of Wild Flowers 
but creep about and vainly fly up towards the light, 
as we can sce by gazing through the screen of hairs. 
But in these attempts at flight they are shaking off 
the pollen they brought from the other flowers, and 
some of this falls upon the visited stigmas and 
fertilises the seed-eges. When these organs are no 
longer susceptible, each excretes from its centre a 
clear drop of nectar, that the flies may drink, and, 
forgetting their enforced imprisonment, go away with 
pleasant recollections of the Cuckoo-pint. 
By the time the refreshments are exhausted the 
anthers have come to maturity, and shed their pollen 
in showers upon the flies, who finally get well covered 
with it. Then the hairs of the barrier shrivel up 
and leave a wide exit up which the Psychode can 
fly, and with still fresh memories of the nectar, they 
seek the freshest Cuckoo-pint in the vicinity to 
repeat the experience, like topers going from tavern 
to tavern. Now, it will be seen that this provision 1s 
a piece of pure altruism in the interest of the species, 
not the individual. The individual’s turn was served 
when the flies brought the pollen from an older 
Cuckoo-pint and fertilised the stigmas. The loading 
of the flies with pollen, and sending them away with 
the pleaswres of their incarceration uppermost in 
recollection, is dictated solely in the interests of the 
species as a whole. 
Where the rare Sweet Flag (Acorus calamus) grows, 
it is interesting to compare it with the Cuckoo-pint. 
Its leaves and stem are very Flag-like, and as it grows 
on the margins of ponds and streams, it may easily 
be overlooked as such. The flowers, to a very large 
number, are crowded round a spadix, but the spathe 
