Bartlett, a peculiar continuous sound. We can, I think,
understand why porcupines have been provided, through the modification
of their protective spines, with this special sound-producing instrument.
They are nocturnal animals, and if they scented or heard a prowling
beast of prey, it would be a great advantage to them in the dark to give
warning to their enemy what they were, and that they were furnished
with dangerous spines. They would thus escape being attacked.
They are, as I may add, so fully conscious of the power of their weapons,
that when enraged they will charge backwards with their spines erected,
yet still inclined backwards.
Many birds during their courtship produce diversified sounds
by means of specially adapted feathers. Storks, when excited,
make a loud clattering noise with their beaks. Some snakes produce
a grating or rattling noise. Many insects stridulate by rubbing
together specially modified parts of their hard integuments.
This stridulation generally serves as a sexual charm or call; but it
is likewise used to express different emotions.[8] Every one who has
attended to bees knows that their humming changes when they are angry;
and this serves as a warning that there is danger of being stung.
Pages:
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150