OLD AGE AND NATURAL DEATH 



A stirring thought; but Johannes Muller had said as much 

 some eighty years beforehand^ and with proper scientific 

 caution had remarked: ''This has the appearance of explaining 

 the phenomena, but is in reahty a mere statement of their 

 connection, and it is not even certain that as such it is 

 correct.** 



Let us now turn to one last famous speculation on the pro- 

 blem of natural death. Minot, we saw, left us with the capacity 

 for growth as an upside-down measure of the rate of ageing. 

 Suppose an animal increased in size indefinitely: would it die a 

 natural death? Hardly, if so important a function as growth 

 were left undimmed by age. But before hearing Bidder''s 

 answer,^ the question can be put a little more exactly. The 

 distinction is not between animals which continue to grow and 

 animals which stop growing but between animals without and 

 with a limit to their size. How the limit is approached is neither 

 here nor there. It may be approached asymptotically, as in 

 mathematical theory, or finally — to a maximum — as for all 

 intents and purposes it is in fact. According to Bidder, fish 

 grow without limit and never undergo senescence nor suffer 

 natural death. Indeed, he does not 'remember any evidence of 

 a marine animal dying a natural death'. Now a mechanical 

 limit is set to the size of animals on land, as Galileo and many 

 others since have taught us; and according to Bidder this limit 

 is set, or has come to be set, by an intrinsic limitation of the 

 power of growth, with senescence as its outcome. ''Did old age 

 and death only become the necessary fate for plants and 

 animals when they left the swamps, claimed the land, and 

 attempted swiftness and tallness in a medium -^^ of their 

 specific gravity?"* Bidder believes that this is so, if the quite 



J. Muller, Elements of Physiology (trans. W. Baly), Vol. 1, pp. 36-6 

 (and cf. Vol. 2, p. 1660), London, 1840-2. 



2 G. P. Bidder, Proceedings of the Linnean Society ^ p. 17, 1932, British 

 Medical Journal, 2, p. 583, 1932. 



31 



