46. Carp, bream, tench, eels, and the like, are not thought to live more than ten years. 47. Salmon are quick of growth but short of life; as also are trout; but perch are slow of growth and long of life. 48. How long the vast mass of matter in whales and sharks is governed by the spirit is not certainly known; nor in seals, sea-hogs and innumerable other kinds of fish. 49. Crocodiles are said to be very long-lived, and likewise to be remarkable for the time of their growth, so that it is thought that they are the only animals which continue to grow as long as they live.1 They are oviparous, voracious, savage, and excellently protected against the water. Concerning the age of the other kinds of shell fish, I find nothing certain is known. Major Observations. From the neglect of observations, and the complication of causes, it is difficult to discover any rule for the length and shortness of life in animals. Some few things however I will note. 1. More birds than beasts are long-lived (as the eagle, vulture, kite, pelican, raven, crow, swan, goose, ibis, parrot, wood-pigeon, and the like); though they complete their growth in a year, and are of less size. Certainly they are excellently protected against the inclemency of the weather; and as they generally live in the open air, they resemble the inhabitants of pure mountains, who are long-lived. Their movements likewise, which (as has been mentioned elsewhere) are partly by carriage and partly by motion of the limbs, 1 Pliny, viii. shake and fatigue them less, and are more healthy. Neither do birds in the first stage of their existence suffer compression or want of aliment in the mother's womb, because the eggs are laid separately. But the principal cause, as I take it, is that birds are made more of the substance of the female than of the male, whence they have a less hot and fiery spirit. 2. It may be laid down that animals which have more of the substance of the female than of the male are longer-lived; as I have just said, birds are. Again, that those which have a longer period of gestation partake more of the substance of the female than of the male, and are therefore more long-lived. Insomuch that even in men (as I have observed in some instances), those who are most like their mother do in my opinion live the longest; as also do the children of old men by young wives, provided the fathers be healthy and not sickly. 3. The beginnings of things are most susceptible both of damage and of help; and therefore the less pressure and the more nourishment that the foetus receives in the womb the more likely is it to be longlived. This happens either when the young are brought forth at separate times, as in birds; or when the birth is single, as in animals which only bring forth one at a time. 4. A long period of gestation lengthens life in three ways. First, as has been said, the young partakes more of the substance of the mother; secondly, it comes forth stronger; and thirdly, it is later in undergoing the predatory action of the air. Besides, it denotes that the periods of nature revolve in larger circles. And though sheep and oxen, which remain about six months in the womb, are short-lived, yet this arises from other causes. 5. Graminivorous and herbivorous animals are shortlived; but those which live on flesh, or even seeds or fruits (as birds do), are long-lived. For stags, which are long-lived, look for half their food (as they say) above their heads; and the goose, besides grass, picks up something in the water to benefit it. 6. The covering of the body I judge to add greatly to longevity, as it prevents and repels the intemperances of the air which so strangely weaken and undermine the body; and with this birds are excellently provided. And though sheep which are well covered are short-lived, this must be attributed to the manifold diseases of the animal and the living upon grass alone. 7. The principal seat of the spirits is doubtless in the head; and though this is commonly referred only to the animal spirits, yet it applies to all. And there is no question that the spirits most absorb and consume the body, so that a larger quantity of them or a greater inflammation and acrimony greatly shortens life. It appears to me therefore that the great cause of longevity in birds is that they have such small heads for the size of their bodies; whence men likewise who have very large heads are, I think, shorter lived. 8. Carriage, as has been before observed, I judge more than any other motion to contribute to longevity. Water-birds, as the swan, are carried on the water; and all birds are carried as they fly, using however from time to time a strong exertion of the limbs. So also are fishes in swimming, but their length of life is uncertain. 9. Animals which come later to perfection (I am not speaking of growth in stature only, but of the other steps to maturity; as man puts out first his teeth, then his signs of puberty, then his beard, &c.), are longer-lived; for it indicates that the periods return in wider circles. 10. The gentler kinds of animals, as the sheep and dove, are not long-lived; for bile acts as a whetstone or spur to many functions of the body, 11. Animals whose flesh is somewhat dark-coloured live longer than those with a white flesh; for it de notes that the juice of the body is firmer, and less easily dissipated. 12. In every corruptible body quantity itself contributes much to the preservation of the whole. For a large fire is not so soon quenched; a small quantity of water evaporates sooner; a twig withers sooner than the trunk. Generally therefore (I speak of kinds, not of individuals) animals of a larger bulk are more long-lived than those of a smaller; unless there is some other powerful cause to prevent it. ALIMENTATION; AND THE WAY OF NOURISHING, to the 4th Article. With reference 1. Nourishment should be of an inferior nature and a simpler substance than the body nourished. Plants are nourished by earth and water, animals by plants, men by animals, There are animals likewise which feed on flesh, and man himself feeds partly on plants; but man and carnivorous animals could hardly be nourished by plants alone. From time and habit they might perhaps be nourished by fruits and seeds that had passed the fire, but not by the leaves of plants or herbs; as has been proved by the order of the Feüillans. 2. Too near a relationship or similarity of substance between the nourishment and the thing nourished does not turn out well. Graminivorous animals do not touch flesh; even of carnivorous animals few eat the flesh of their own species; nor do men that are cannibals feed ordinarily upon man's flesh, but take to it either for revenge on their enemies, or from some unnatural custom. A field is not well sown with the grain which grew in it, nor is the sucker or shoot grafted on its own stock. 3. The better the aliment is prepared, and the nearer it assimilates to the substance of the thing nourished, the more fruitful do plants become, and the more do animals fatten. For no shoot or sucker planted in the ground is so well nourished as if it were grafted on a stock well suited to its nature, where it found its nourishment digested and prepared. Neither (it is said) will the seed of an onion or the like, put into the earth, produce so large a plant as it would if it were first grafted into the root of another onion, and then put into the earth. Again, it has been recently discovered that shoots of wild trees, as the elm, oak, ash, and the like, bear far larger leaves when grafted on other stocks than they do naturally. Men likewise are better nourished by cooked than by raw food. 4. Animals are nourished through the mouth, plants through the roots, the foetus of animals in the womb through the navel cord, and birds for a short time by the yolk of their eggs, some of which is even found in their crops after they are hatched. 5. All aliment moves principally from the centre |