nature, a great check to increase is to be found in the difficulty the seeds experience in finding a proper soil in which to germinate, as well as in other sources of destruction.
The advantages of, or the part played by fecundity in the preservation of many species is evidently of the most complete and far-reaching character. This seems particularly and more frequently the case with fishes,[1] the reasons for which are not difficult to comprehend. It has been urged that the pale colour of the under side of fishes makes it more difficult for enemies to detect them from beneath; but this is probably a truism without denoting any evolved protection, and may be due to other causes. The survival is probably owing to fecundity alone, which prevents extermination from the many foes and adverse conditions which environ their lives. One may stand before the tank in a large aquarium, and be impressed with the assimilative colouration of the upper sides of flat-fishes to the sandy or pebbly bottom on which they rest, but still no difficulty is experienced in distinguishing the living creatures; and if this be so, and with our untrained perceptions, how much stronger must be the detective powers of those natural enemies whose prey is their necessity! The 130,000 eggs said to be carried by a Sole of one pound weight is probably the factor which prevents annihilation, and not a moderate disguise which, without deceiving ourselves, is still less likely to mislead enemies whose lives depend on its destruction. Nature is here quite "careless of the single life," but, by fecundity, "so careful of the type." In our oceans and rivers the course of evolution has decided that the most prolific shall survive, and this is probably with fish the great factor of protection. Here individuality is lost, and Providence is with the big battalions.
- ↑ Of course it is not suggested that all fish survive through fecundity alone. The European Goby (Latrunculus pellucidus) and the Sea-Stickleback (Gastrosteus spinachia) have apparently been proved to die within a year of their birth. In these cases other protection seems to be afforded. According to Dr. Günther, the fish spawns in June and July. In April the males lose the small teeth, which are replaced by very long and strong teeth, the jaws themselves being stronger. The teeth of the females remain unchanged. In July and August all the adults die off ('Introd. Study Fishes,' p. 487). In this case the male may defend the progeny. G. spinachia is, on the same authority, a "nest builder, choosing for its operations especially the shallows of brackish water which are covered with Zostera." (ibid. p. 507).
