OLD AGE AND NATURAL DEATH 



Child told us;i of certain sea-squirts, and of the aberrant, worm- 

 like creatures known as Nemertines.^ These latter have the 

 advantage of the rat, for if deprived of food they react by- 

 growing smaller, thus literally retreating into second childhood. 

 They do not quite exactly retrace their steps, ''advancing back- 

 wards'* (as was said of a recent famous military campaign) along 

 the path they followed in development; but in a sense they 

 cheat Time. The fact that starved rats outlive those which 

 habitually eat sufficient is often used as evidence of the rela- 

 tivity of biological time; but in reality, it is evidence less of the 

 tortuous mysteries of time and space than of the virtues of 

 sobriety and moderation. 



In the extreme case, when life is held altogether in abeyance, 

 we may properly speak of immortality. Freeze a tissue such as 

 mammalian skin to the temperature of liquid air (something 

 less cold will do) and the resumption of life will then await the 

 convenience of the experimenter.^ The idea is an old one. 

 Until he tried to freeze two carp, John Hunter — * 



'imagined that it might be possible to prolong life to any period 

 by freezing a person. ... I thought that if a man would give up 

 the last ten years of his life to this kind of alternate oblivion and 

 action, it might be prolonged to a thousand years; and by getting 

 himself thawed every hundred years, he might learn what had 

 happened during his frozen condition. Like other schemers, I 

 thought I should make my fortune by it; but this experiment 

 undeceived me.' 



1 C. M. Child, Senescence and Rejuvenescence, Chicago, 1915. 



2 See J. Needham, Biochemistry and Morphogenesis, pp. 524-9, Cam- 

 bridge, 1942. 



3 Cf. R. Briggs and L. Jund, Anatomical Record, 89, p. 75, 1944; J, P. 

 Webster, Annals of Surgery, 120, p. 431, 1944. The author has often 

 confirmed their observations. [See R. E. Billingham and P. B. Medawar, 

 Journal of Experimental Biology, 29, p. 454, 1952.] 



* J. Hunter, Of the Heat of Animals, in The Works of John Hunter, 

 F.R.S., ed. J. F. Palmer, Vol. 1, p. 284. The phenomenon which Hunter 

 unluckily failed to demonstrate has been called 'anabiosis'. 



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