18. And all animals with mouths receive pain or pleasure from the contact of food. But, concerning the senses of sight and hearing, it is not possible to say anything certain, or very distinct; the solens, if a person touch them, appear to retract themselves, and try to escape when they see an instrument approaching them, for a small portion of them is beyond the shell, the remainder as it were in a retreat; the pectens, also, if a finger is brought near them, open and shut themselves as if they could see.
19. Those who seek for neritæ do not approach them with the wind, when they seek them for baits, nor do they speak, but come silently, as if the creatures could both smell and hear; they say that if they speak, they get away. Of all testacea, the echinus appears to have the best sense of smell amongst those that can move, and the tethya and balanus in those that are fixed. This is the nature of the organs of sense in all animals.
Chapter IX.
1. The following is the nature of the voice of animals, for there is a distinction between voice and sound. Speech, again, is different from these. Voice is due to no other part except the pharynx, the creatures, therefore, without lungs are also without voice. Speech is the direction of the voice by the tongue; the vowels are uttered by the voice and the larynx, the mutes by the tongue and the lips; speech is made up of these: wherefore, no animals can speak that have not a tongue, nor if their tongue is confined.
2. The power of uttering a sound is connected with other parts also; insects have neither voice nor speech, but make a sound with the air within them, not with that which is external, for some of them breathe not, some of them buzz, as the bee with its wings, and others are said to sing, as the grasshopper. All these make a noise with the membrane which is beneath the division of their body in those which have a division, as some families of grasshoppers by the friction of the air. These insects, bees, and all other insects raise and depress their wings in flight, for the sound is the friction of the air within them. Locusts produce a sound by rubbing themselves with their legs, which are adapted for leaping. None of the malacia utter any sound or natural voice, nor do the malacostraca.
3. Fish also are mute, for they have neither lungs, trachea, nor pharynx. Some of them utter a sound and a squeak; these are said to have a voice, as the lyra[151] and chromi,[152] for these utter, as it were, a grunt; so does the capros, a fish of the Achelous, the chalceus[153] and coccyx,[154] for the one utters a sound like hissing, the other a noise like that of the cuckoo, from whence also its name is derived. Some of these utter their apparent voice by the friction of their gills, for these places are spinous, in others the sound is internal, near the stomach. For each of them has an organ of breathing, which causes a sound when it is pressed and moved about.
4. Some of the selachea also appear to whistle, but they cannot be correctly said to utter a voice, only to make a sound. The pectens also make a whizzing noise when they are borne upon the surface of the water, or flying, as it is called; and so do the sea-swallows,[155] for they also fly through the air in the same way, not touching the sea, for they have wide and long fins. As the sound made by birds flying through the air is not a voice, so neither can either of these be properly so called. The dolphin also utters a whistle and lows when it comes out of the water into the air, in a different way from the animals above-mentioned—for this is a true voice, for it has lungs and a trachea, but its tongue is not free, nor has it any lips so as to make an articulate sound.
5. The oviparous quadrupeds, with a tongue and lungs, utter a sound, though it is a weak one. Some of them hiss like serpents; others have a small weak voice, others, as the tortoise, utter a small hiss. The tongue of the frog is peculiar, for the fore-part of it is fixed, like that of a fish; but the part near the pharynx is free and folded up. With this it utters its peculiar sound. The male frogs make a croaking in the water when they invite the females to coition.
6. All animals utter a voice to invite the society and proximity of their kind, as the hog, the goat, and the sheep. The frog croaks by making its lower jaw of equal length, and stretching the upper one above the water. Their eyes appear like lights, their cheeks being swelled out with the vehemence of their croaking; for their copulation is generally performed in the night. The class of birds utter a voice: those which have a moderately wide tongue have the best voice; those also in which the tongue is thin. In some kinds both male and female have the same voice; in others it is different: the smaller kinds have more variety in their voice, and make more use of it, than the larger tribes.
7. All birds become more noisy at the season of coition. Some utter a cry when they are fighting, as the quail; others when they are going to fight, as the partridge; or when they have obtained a victory, as the cock. In some kinds both male and female sing, as the nightingale; but the female nightingale does not sing while she is sitting or feeding her young: in some the males alone, as the quail and the cock; the female has no voice. Viviparous quadrupeds utter different voices; none can speak—for this is the characteristic of man, for all that have a language have a voice, but not all that have a voice have also a language.