MUR^ENID^E. 247 



Parasitic worms, Ascaris, have been constantly pointed at in the intestines 

 of these fish as the developing young ; while other fishes have likewise been the 

 reputed parents of eels. Jacoby tells us that this last opinion is even very 

 prevalent at the present day among eel fishermen, especially such as reside 

 near the mouths of rivers. A slimy fish, Zoarces viviparus (see vol. i, p. 211), 

 owes the name by which it is generally known in Commachio the " eel-mother " 

 to this opinion. It is a very old opinion, prevalent to this day, that eels copulate 

 with water-snakes, but it seems incredible, and is nevertheless a positive fact, that 

 the Sardinian fishermen consider a beetle, Dytiscus Boeselii, as the procreator of 

 the eel. 



In the seventeenth century Redi and Paullini both expressed their opinions 

 that eels must have both semen and ova; while Mondini, at Bologna, in 1777, 

 read an accurate description, accompanied by excellent illustrations of the ovaries 

 of the eel discovered by himself, and which was published in 1 783. 0. F. Midler 

 almost simultaneously (1780) published a description of the ovaries of this fish, 

 which appear in the shape of a frill-shaped band, extending in the abdomen 

 anteriorly to the forepart of the liver and posteriorly to the vent,* while in this 

 band are numerous eggs, but no duct, as the ova falls into the abdominal -cavity. 

 Rathke, in 1850, described the first gravid female eel which up to that period had 

 come into the hands of a competeut investigator. For some time it was contended 

 that this fish was an hermaphrodite, and it was not until 1873 that Syrski, at 

 Trieste, obtained an eel 15 inches long possessing an undescribed organ as well as 

 being deficient in an ovary. This lobe-organ consists of tubes in areolar tissues, 

 contains a seminal duct, shows no trace of frill-like folds, but appears as a light 

 band with a free edge. Care has to be taken not to mistake two fatty bands, which are 

 always present in either sex of eels, for the lobe-organ. The largest male seen by 

 Syrski has been from 17 to 19 inches in length. Since they were first detected 

 numerous male examples have been found. 



Gunther, in his "Introduction to the Study of Fishes" (1880), disposes of 

 the investigations made up to that period, remarking: " Their mode of propa- 

 gation is still unknown. So much only is certain, that they do not spawn in 

 fresh water, that many full-grown individuals, but not all, descend rivers during 

 the winter months, and that some of them spawn in brackish water, or in deep 

 water in the sea." The common opinion seems to be that the eel only spawns 

 once in its lifetime, a peculiarity it shares with the lamprey, and this pi'ocess 

 takes place in the sea. The proportion of male to female fish rapidly decreases 

 with the distance from the sea. When the young are hatched they ascend the 

 rivers to reach the inland streams and ponds, where they grow in size but never 

 increase in numbers. It would seem, considering the state of the ovaries so 

 long as these fish continue in rivers, that salt water is needed to develop the 

 pro creative powers. 



Life history. It has been disputed whether young eels grow rapidly or 

 slowly. f M. Coste says that placed in reservoirs with plenty of food, in four or 

 five years they weigh from 4 to 6 lb. I received alive through the post a little 

 elver, 2T inches long, on May 15th, 1879, at Cheltenham. It did well when 

 placed in an aquarium, usually lying on the top of the Valisneria in the water, 

 and darting away and hiding its head under a stone if frightened : occasionally it 

 ascended to the surface and discharged a bubble of air. By May 27th it had 

 grown to 3| inches in length, during this period having been kept in a tumbler 

 with about two inches of tank water changed daily. It was now taken to Weston- 

 super-Mare, but did not thrive, the water apparently being unsuited. At the end 

 of June it was brought back to Cheltenham, but during my absence died, due to 

 rain water only having been supplied. 



Fisheries. There are many celebrated ones distributed over Europe, more 

 especially that of Commachio, near Venice : those of the Seine in France, Nar- 



* The genital opening is a simple orifice which communicates with both halves of the abdominal 

 cavity by means of a transverse fissure between the rectum and the urinary bladder, and opens into 

 the urethra. 



f Cultivation of Eels, Souberain, A. M. N. H. (3), 1865, xvi, p. 384. 



