116
THE ESSEX NATURALIST.
The throwing-up of "pellets" is advantageous to those birds
which practise the habit, since they are by this means spared
certain internal complications from which other less-fortunate
animals suffer.
Thus, the Persian Goat not uncommonly forms concretionary
masses in its intestine from the non-digestible food, which
are known as "bezoar-stones"; and similar concretions have
been met with, as abnormal products, in the intestines of
various deer, antelopes and monkeys, and are regarded in
the East as possessing medicinal qualities; while in the crayfish
a pair of limy concretions are normally formed in the gizzard,
and are credited by German peasants with magical properties.
The perfume "ambergris" is a faecal concretion formed in
the intestine of the sperm whale, and contains fragments of
the hard parts of the cuttle-fishes upon which the whale feeds.
Various herbivorous animals, too, form what are known as.
"hair-balls" in their intestines.
These are more or less pathological manifestations, men-
tioned here only to show the need which many and diverse
creatures experience to get rid of the non-assimilable residue.
of their food, a need which birds have so admirably met by the
habit of regurgitation. Somebody has well said that vomiting
comes easy to birds, the wide gape, the short distensible aeso-
phagus and the strongly muscular crop which they possess,
rendering the process an easy one.
But not birds alone, though chiefly they, possess the pellet-
casting method of ridding themselves of the indigestible residue
of their food; other classes of animals, at least occasionally,
exhibit the same habit. Certain reptiles and amphibians,
for instance, eject "pellets." It is recorded of Natterjack
Toads that "when captured and placed in a box they vomit
pellets of wing cases and the indigestible parts of the harder
beetles."4 The Rattlesnake is similarly credited. An observer
records, "Another strange observation was that sometimes these
snakes disgorge pellets composed of hairs and feathers, after
the manner of owls,"5 and a Leopard Snake (Coluber leopardinus),
kept in captivity for a year, exhibited the same method of getting
rid of indigestible food. "Its last meal, which consisted of two
mice, it disgorged about five days afterwards."6
4 Zoologist, 1914, p. 388.
5 Bulletin de la Societe Zool. de France, 1897, p. 187. Zoologist, 1898, p. 93.
6 Zoologist, 1901, p. 159.