"The generation of the eel was long involved in great mystery, and the knowledge thereof is one of the recent acquisitions of scientific investigation. So late, indeed, as 1880 it was declared that 'their mode of propagation is still unknown.' In want of positive knowledge the rein has been given to loose hypothesis and conjecture. It has been variously asserted that eels were generated from slime, from dew, and from the skins of old eels or of snakes. The statement that they come from horse-hairs is familiar to many country boys, and the origin of this belief is due simply to the fact that there are certain aquatic worms, known under the generic name _Gordius_, which are elongated and apparently smooth like the eel, and which may be found in the same waters. It was one of the ideas of the Greek to attribute their paternity, as of many other doubtful offspring, to the convenient Jupiter. The statement that they are viviparous has arisen from two causes: one the existence of intestinal worms, and the other from the confusion of the eel with an elongated and consequently eel-like but otherwise very different form, the _Zoarces viviparus_. The _Zoarces_ is indeed, in Germany as well as in the Scandinavian countries, generally known as the Aal-mutter, or eel-mother, and thus in its name perpetuates the fancy. Even where eels are to be found in extreme abundance, and where they are the objects of a special culture, like erroneous opinions prevail. Thus, according to Jacoby, about the lagoon of Comacchio there is an 'ineradicable belief among the fishermen that the eel is born of other fishes; they point to special differences in color and especially in the common mullet, _Mugil cephalus_, as the causes of variation in color and form among eels. It is a very ancient belief, widely prevalent to the present day, that eels pair with water-snakes. In Sardinia the fishermen cling to the belief that a certain beetle, the so-called water-beetle, _Dytiscus ræselii_, is the progenitor of eels, and they therefore call this "mother of eels."' The assignment of such maternity to the water-beetle is doubtless due to the detection of the hair-worm, or Gordius, in the insect by sharp-sighted but unscientific observers, and, inasmuch as the beetle inhabits the same waters as the eel, a very illogical deduction has led to connect the two together.