III.— THE PROPAGATION OF THE EEL 



By Dr. Otto Hermes.' 



[From Circular No. 6, Berlin, November 25, 1880, of the " Deutsche Fischerei- 

 Verein" — German Fishery Association.] 



Since the beginning of last spring, when the eel fisheries in our part 

 of the country commenced, I have given my undivided attention to the 

 eel question (see Circular No. 1, p. 23 ; No. 2, p. 55 ; No. 4, p. 72, 1880), 

 to dispel, if possible, the darkness which still hides the life of this mys- 

 terious fish. I do not hesitate to communicate, at the present time, the 

 results of my investigations to the readers of the Circular, with the hope 

 of stimulating others to make observations of this problem. 



It was natural to extend these investigations to the formation and 

 development of the sexual organs of the sea eel (Conger vulgaris), which 

 so closely resembles the fresh-water eel, all the more as its sexual 

 organs and the manner in which it reproduces its species are likewise 

 but little known. If positive facts could be ascertained with regard to 

 this eel, it would be tolerably safe to conclude, from the similarity of 

 the two kinds of fish, that the same would apply to our common river 

 eel (Anguilla fluviatilis). 



The sea eel grows twice as long as our river eel (specimens measuring 

 6 feet in length are by no means uncommon), and outwardly differs from 

 the latter by the different formation of the jaws and the dorsal fin. In 

 the sea eel the latter begins immediately back of the pectoral fins, whilst 

 in the river eel it is placed farther back. In the sea eel the upper jaw 

 protrudes over the lower jaw ; in the river eel the reverse is the case. 

 The position and formation of the internal, especially the sexual, organs 

 is very similar in both. But whilst the river eel grows up in rivers and 

 only goes into the sea to spawn, the sea eel never leaves the sea. The 

 sea eel stands imprisonment very well, and grows rapidly. I have had 

 a considerable number in the Berlin Aquarium, and have examined 

 several large ones which died. These were invariably female fish, 

 whose ovaria had developed to an extraordinary degree. From lack of 

 the natural conditions they could probably not spawn, and I believe 

 that they died from this cause. I have been informed that a sea eel in 

 the aquarium in Frankfort on-the-Main actually burst in consequence of 

 the unnatural development of the ovaria. 



* Zur Fortpflanzung des Aales, von Dr. Otto Hermes.— Translated by Herman Jacob- 

 eon. 457 



