LARVA GF THE COMMON EEL.

Hawke's Bay Herald, Volume XXXII, Issue 10657, 10 July 1897, Page 6

LARVA GF THE COMMON EEL.

There has hitherto boon a mystery in j tba life-history of the common eel which , has defied tho lrquisltlveneas of the I most Industrious ichthyologist. It has, however, long been suapectod that the singular marine organisms known as leptodepbalus were the normal larvas of fishes of the 00l family, and in the case of leptooophali Morrlalt it has been proved by Mr Ivea Delage experimentally that it changed into a young conger. But with regard to the common eel, the conneotion between the supposed larva and the developed fish has not until now been traced, For some years past two Italian ichthyologists, Slgnorea Grasai and Oalandrucolo, have been working at this problem, and lately they have contributed to the Royal Society a full and interesting aooount of their investigations. A large number of livine specimens of leptocephall are usually several inches In length, tbin and of uniform breadth like a piece of ribbon, very transparent and unpigmonted. The blood is not red, there is no air bladder, and internally the body consists largely of a peculiar gelatinous tisaCej Tiie metamorphosis of a large number of these peculiar creatures has been traced with' complete continuity Into various speoies of Mcraenide, but it was not until 1893 that one, remarkable for its small sizs, was aa.ipected to be the larva of the common eel. Messrs, Grassi and Calandruooio have even yet not been able to follow the entire metamorphosis in one and the same specimen, bat they have verified the most important changes in spooimena kept in confinement, and compared all the organs In various stages with those in the perfoot form ( and they now declare leptocephalus Crovirostris to be the larva of the common eel. Prom their observations they are led to the belief that thfl spawning of the eel and other Huraemdne, and the development of the egeasnd larra, tafte place normally at great depths— st least 250 fathoms— and the larvffl ate carried to the surface with deep sen fishes by the movements of the water. It is n curious fact that the larvaj, now idontified as those of the eel, are found in the greatest abundanoe In the stomach of the sun- fish, which Is a deep" water speoies. Grassi, by tracing baokwards the succession of events in tho origin and development of young ! eels, comes to the conclusion that the ' elvers or eel-faro whioh ascend our rivers are already about a year pld when they come into fresh water.