[2771] It has been calculated, Cuvier says, that a female cod, or sturgeon, produces in a year more than one hundred thousand eggs.
[2772] Cuvier says, that the eggs of the common fishes, of toads, frogs, &c., have no shells, but only a membranous tunic; and when they have been once fecundated, they imbibe the surrounding moisture, and increase till they produce the animal.
[2773] It is probable, Cuvier thinks, that this passage relates more especially to the ray genus, but that there is no very positive knowledge as to the mode in which they do couple. It is probable, he suggests, that they may do it in the manner above mentioned, by the attrition of the belly. As to the turtle genus, he says, it is certain that the male mounts the back of the female; and in some species the sternum of the male is concave, the better to adapt itself to the convex callipash of the female.
[2774] More properly, the physeter, passage, or orifice.
[2775] Cuvier remarks, that this account of the coupling of the cephalopodes is taken from Aristotle. He says, that he is not aware whether modern observation has confirmed these statements, and almost doubts whether, considering the organization of these animals, it is not almost more probable that they do not couple at all, and that the male, as in the case of most other fishes, only fecundates the eggs after they have been deposited by the female.
[2776] Cuvier says, that whatever may be the sense in which the word “mollia” is here taken, the assertion is not correct. The gasteropod molluscs, he says, whether hermaphroditical, or whether of separate sexes, couple side to side. The acephalous molluscs do not couple at all, and each individual fecundates its own eggs. The crustacea couple by attrition of the belly.
[2777] “Tadpoles.” There is both truth and falsehood, Cuvier says, in the statements here made relative to the tadpole. Frogs, he says, produce eggs, from which the tadpole developes itself, with a tail like that of a fish. The feet, however, are not produced by any bifurcation of the tail, but shoot out at the base of the tail, and in the same proportion that they grow, the tail decreases, till at last it entirely disappears.
[2778] Frogs, Cuvier says, conceal themselves in mud and slime during the winter, but, of course, are not changed into it.
[2779] “Quæ fuere.” Just in the same state, he probably means to say, in which they were when they were melted into slime, and not as they were when in the tadpole state.
[2780] All that is asserted here, Cuvier says, about the spontaneous operations of nature is totally false. Everything connected with the eggs and the generation of the mussel, the murex, and the scallop is now clearly ascertained.