PHYSIOLOGY 191 



too, have their age periods, only these are sometimes infinitely 

 shorter, and are reckoned by days instead of years. 



The closest parallels are found in the life-story of the higher 

 orders of animals, though even here there are many and im- 

 portant differences. The childhood free from care gives place 

 at once to the stern battle of life, when the parents turn out of 

 the nest or lair their offspring as self-supporting ; only among 

 those animals that maintain the family ties do the youngsters 

 remain longer under the family protection. 



Puberty occurs, as a rule, earlier in the higher animals than 

 in man, and forthwith the sexes seek and find each other ; they 

 have no need, even if they could conceive such a thing, of 

 "enthusiasm for ideals". But as in man these years represent 

 the fulness of mental and physical vigour, and as in man the 

 horizontal line of life gradually inclines downwards until it 

 reaches the rapid slope of old age, till death occurs either at 

 the hand of some more powerful beast or man, or from some 

 physical misfortune and disease. 



The strangest fables may be unearthed about the length 

 of life attained either by man or beast in ancient times, as 

 may be instanced from the ages of the so-called patriarchs or 

 from such poets as Hesiod. 



DE ^TATIBUS ANIMALIUM. 



Ter binos deciesque novem super exit in annos 

 Justa senescentum quos implet vita virorum ; 

 Hos novies superat vivendo garrula comix, 

 At quater egreditur cornicis secula corvus. 

 Alipedem cervum ter vincit corvus, et ilium 

 Multiplicat novies Phoenix, reparabilis ales, 

 Quam vos perpetuo decies praeventitis aevo, 

 Nymphae Hamadryades, quarum longissima vita est. 

 Hi cohibent fines vivacia fata animantum. 



Reliable data can be obtained only as to the length of life 

 in man, domestic animals and wild animals in captivity. 



According to Ellenberger, 1 who seems to depend himself on 

 Weismann's researches, the duration of life should be six times 

 the period of growth, and he gives the following table of 

 maximum ages : 



1 Ellenberger, loc. cit., ii., p. 585. 



