on longevity and shortness of life-第2节

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animals　that　are　large　are；　as　a　general　rule；　longer…lived　than　the



rest；　as　was　said　before；　it　is　to　be　expected　that　the　larger



should　contain　more　moisture。　But　it　is　not　merely　this　that　makes



them　longer　lived；　for　the　cause　is　twofold；　to　wit；　the　quality　as



well　as　the　quantity　of　the　fluid。　Hence　the　moisture　must　be　not　only



great　in　amount　but　also　warm；　in　order　to　be　neither　easily　congealed



nor　easily　dried　up。



　　It　is　for　this　reason　also　that　man　lives　longer　than　some　animals



which　are　larger；　for　animals　live　longer　though　there　is　a　deficiency



in　the　amount　of　their　moisture；　if　the　ratio　of　its　qualitative



superiority　exceeds　that　of　its　quantitative　deficiency。



　　In　some　creatures　the　warm　element　is　their　fatty　substance；　which



prevents　at　once　desiccation　and　congelation；　but　in　others　it　assumes



a　different　flavour。　Further；　that　which　is　designed　to　be　not



easily　destroyed　should　not　yield　waste　products。　Anything　of　such　a



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。







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　　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…



。