The Mortality of Plaice

The biology of senescence

“…There are also general developmental theories which stress the continuity of senescence with morphogenesis (Baer, 1864;Cholodkowsky, 1882; Roux, 1881; Delage, 1903; Warthin, 1929) or the operation of an Aristotelean entelechy (Driesch, 1941;Burger, 1954), metabolic theories introducing the concept of a fixed-quantity reaction or of a rate/quantity relationship in determining longevity (Rubner, 1908;Loeb, 1908;Pearl, 1928; Robertson, 1923), attainment of a critical volume-surface relationship (Muhlmann, 1910 etc. ), depletive theories relating senescence to reproduction (Orton, 1929) and finally an important group of theories which relate senescence to the cessation of somatic growth (Minot, 1908; Carrel and Ebeling, 1921;Brody, 1924;Bidder, 1932; Lansing, 1947Lansing, , 1951. Most of the older theories have been reviewed, against a background of Drieschian neovitalism, in the textbook of Burger (1954).…”

“…Little need be said of the various toxic or pathological theories of mammalian senescence. We are really left with five historically important theories, or groups of observations: the suggestion of Weismann that senescence is evolved, not intrinsic in all cellular matter; the work of Pearl (1928) which leads to the conception of a 'rate of living', such that factors which retard development or reduce metabolism tend in many organisms to prevent or postpone senescence; the work of Minot (1913Minot ( , 1908, of which the most important surviving parts are his relation of senescence to the decline of growth, and his insistence upon its continuous and gradual character and its continuity with morphogenesis; the experimental studies of Child (1915), which showed that cellular differentiation and 'senescence' in planarians is reversible, and of Carrel (1912), who demonstrated that some tissue cells derived from adult animals could be propagated indefinitely in vitro, and finally the theories of Bidder (1932).…”

Immortality and Pearl's Survivorship Curve for Hydra

“…The same paper refers favorably to the report of Bidder (1925), who suggested potential immortality for the female plaice and for other aquatic forms in which the absence of senescence was associated with never-ending growth. Stiven (1962) suggests that the deaths of Rase's hydras (Hase 1909) might have been due to toxicity of the "Berlin tap water," or to other defects in Rase's culture conditions, implying that Pearl's survivorship curve would be invalid if the deaths were not due to "old age."…”

Aging versus Growth

“…Although the males evidently die after spawning, the females continue to enlarge, some of them reaching weights of 6 kg. Bidder [4] determined that the growth coefficient of the plaice ovaries was 1.6, which means that the larger the fish grows, the greater the percentage of body weight represented by the ovaries. It was predicted that the ovaries would represent one-half the body weight when the fish grew to 6 kg.…”