“…An example of this second category is the determination of the future size of adult populations of marine fishes by the effects of various environmental agencies upon the early developmental stages (Hjort, 1914;Johnstone, 1928). Presumably the periodic oscillations in the numbers of fur-bearing mammals and game birds which have been synchronized with sunspot cycles (Elton, 1924;Gross, 1931;Naumov, 1939;Braestrup, 1940;Green and Evans, 1940) result from complexes of environmental vectors whose action is more or less delayed.…”