(though more speedily) when scattered. Now this way of perishing is

due to violence equally in living and in lifeless objects, for the

division of an animal by instruments and consequent congelation by

excess of cold cause death. But exhaustion is due to excess of heat;

if there is too much heat close at hand and the thing burning does not

have a fresh supply of fuel added to it, it goes out by exhaustion,

not by the action of cold. Hence, if it is going to continue it must

be cooled, for cold is a preventive against this form of extinction.



15



Some animals occupy the water, others live on land, and, that being

so, in the case of those which are very small and bloodless the

refrigeration due to the surrounding water or air is sufficient to

prevent destruction from this cause. Having little heat, they

require little cold to combat it. Hence too such animals are almost

all short-lived, for, being small, they have less scope for deflection

towards either extreme. But some insects are longer-lived though

bloodless, like all the others), and these have a deep indentation

beneath the waist, in order to secure cooling through the membrane,

which there is thinner. They are warmer animals and hence require more

refrigeration, and such are bees (some of which live as long as

seven years) and all that make a humming noise, like wasps,

cockchafers, and crickets. They make a sound as if of panting by means

of air, for, in the middle section itself, the air which exists

internally and is involved in their construction, causing a rising and

falling movement, produces friction against the membrane. The way in

which they move this region is like the motion due to the lungs in

animals that breathe the outer air, or to the gills in fishes. What

occurs is comparable to the suffocation of a respiring animal by

holding its mouth, for then the lung causes a heaving motion of this

kind. In the case of these animals this internal motion is not