八喜电子书 > 经管其他电子书 > on longevity and shortness of life >

第2部分

on longevity and shortness of life-第2部分

小说: on longevity and shortness of life 字数: 每页4000字

按键盘上方向键 ← 或 → 可快速上下翻页,按键盘上的 Enter 键可回到本书目录页,按键盘上方向键 ↑ 可回到本页顶部!
————未阅读完?加入书签已便下次继续阅读!





nature causes death either by disease or naturally; for the potency of



the waste product works adversely and destroys now the entire



constitution; now a particular member。



  This is why salacious animals and those abounding in seed age



quickly; the seed is a residue; and further; by being lost; it



produces dryness。 Hence the mule lives longer than either the horse or



the ass from which it sprang; and females live longer than males if



the males are salacious。 Accordingly cock…sparrows have a shorter life



than the females。 Again males subject to great toil are short…lived



and age more quickly owing to the labour; toil produces dryness and



old age is dry。 But by natural constitution and as a general rule



males live longer than females; and the reason is that the male is



an animal with more warmth than the female。



  The same kind of animals are longer…lived in warm than in cold



climates for the same reason; on account of which they are of larger



size。 The size of animals of cold constitution illustrates this



particularly well; and hence snakes and lizards and scaly reptiles are



of great size in warm localities; as also are testacea in the Red Sea:



the warm humidity there is the cause equally of their augmented size



and of their life。 But in cold countries the humidity in animals is



more of a watery nature; and hence is readily congealed。



Consequently it happens that animals with little or no blood are in



northerly regions either entirely absent (both the land animals with



feet and the water creatures whose home is the sea) or; when they do



occur; they are smaller and have shorter life; for the frost



prevents growth。



  Both plants and animals perish if not fed; for in that case they



consume themselves; just as a large flame consumes and burns up a



small one by using up its nutriment; so the natural warmth which is



the primary cause of digestion consumes the material in which it is



located。



  Water animals have a shorter life than terrestrial creatures; not



strictly because they are humid; but because they are watery; and



watery moisture is easily destroyed; since it is cold and readily



congealed。 For the same reason bloodless animals perish readily unless



protected by great size; for there is neither fatness nor sweetness



about them。 In animals fat is sweet; and hence bees are longer…lived



than other animals of larger size。







                                 6







  It is amongst the plants that we find the longest life…more than



among the animals; for; in the first place; they are less watery and



hence less easily frozen。 Further they have an oiliness and a



viscosity which makes them retain their moisture in a form not



easily dried up; even though they are dry and earthy。



  But we must discover the reason why trees are of an enduring



constitution; for it is peculiar to them and is not found in any



animals except the insects。



  Plants continually renew themselves and hence last for a long



time。 New shoots continually come and the others grow old; and with



the roots the same thing happens。 But both processes do not occur



together。 Rather it happens that at one time the trunk and the



branches alone die and new ones grow up beside them; and it is only



when this has taken place that the fresh roots spring from the



surviving part。 Thus it continues; one part dying and the other



growing; and hence also it lives a long time。



  There is a similarity; as has been already said; between plants



and insects; for they live; though divided; and two or more may be



derived from a single one。 Insects; however; though managing to



live; are not able to do so long; for they do not possess organs;



nor can the principle resident in each of the separated parts create



organs。 In the case of a plant; however; it can do so; every part of a



plant contains potentially both root and stem。 Hence it is from this



source that issues that continued growth when one part is renewed



and the other grows old; it is practically a case of longevity。 The



taking of slips furnishes a similar instance; for we might say that;



in a way; when we take a slip the same thing happens; the shoot cut



off is part of the plant。 Thus in taking slips this perpetuation of



life occurs though their connexion with the plant is severed; but in



the former case it is the continuity that is operative。 The reason



is that the life principle potentially belonging to them is present in



every part。



  Identical phenomena are found both in plants and in animals。 For



in animals the males are; in general; the longer…lived。 They have



their upper parts larger than the lower (the male is more of the dwarf



type of build than the female); and it is in the upper part that



warmth resides; in the lower cold。 In plants also those with great



heads are longer…lived; and such are those that are not annual but



of the tree…type; for the roots are the head and upper part of a



plant; and among the annuals growth occurs in the direction of their



lower parts and the fruit。



  These matters however will be specially investigated in the work



On Plants。 But this is our account of the reasons for the duration



of life and for short life in animals。 It remains for us to discuss



youth and age; and life and death。 To come to a definite understanding



about these matters would complete our course of study on animals。











                                   …THE END…






返回目录 上一页 回到顶部 0 0

你可能喜欢的