286 The Bird 
gigantic size than one which has to support its body in 
the thinner atmosphere: a whale is to a horse as an 
ostrich is to a dove. 
The ostrich is the largest of all living birds, a full- 
grown male being able to reach to a height of nine feet 
and weighing as much as three hundred pounds; but 
even these figures were exceeded by its extinct relative 
of Madagascar, the moa, whose height is variously esti- 
mated at from ten to eleven feet, and whose massive leg- 
bones show that its weight must have been much greater 
than that of the ostrich. 
There is a great difference in the relative condition 
of the body in various birds. Herons, even when fish 
are abundant, with opportunities of feeding from morn- 
ing to night, are thin to emaciation. Truly they belong 
to the ‘lean kine.’ A fat heron would be an anomaly. 
On the other hand, the flesh of many sea-birds seems as 
constantly encased in thick, oily layers of fat. Petrels 
are used by the inhabitants of some islands as candles, 
simply by threading the body of the dead bird with a 
wick, the excess of fat burning steadily until the whole is 
consumed. Penguins are well protected against the icy 
waters of their Antarctic home by a layer of fat under 
the skin, so thick in proportion to their size as to remind 
one of the blubber of whales. 
If we were writing of the bodies of the fur-bearers 
instead of birds, we would have much to say concerning 
the various kinds of scent-glands and secreted odours; 
but in birds the only gland is that above the tail, which 
furnishes the oil with which the bird preens its plumage, 
