BULLETIN OF THE UNITED STATES FISH COMMISSION. 97 



and who jirououuced upon the emi^ty ovaries in these dead fish is un- 

 fortunately not mentioned. 



A great number of the eels remain in inland waters while others 

 proceed to the sea, either because their eggs are at this time not suffi- 

 ciently ripe, or i^erhaps because they are sterile. It would seem prob- 

 able that the increase in the size of the eggs in the wandering eels 

 begins to be very ^apid after August and September, while in the 

 earlier months of the year, in all eels of moderate size, the eggs were 

 at the utmost biit about 0.00 in diameter. In September of the srime 

 yiear, I found (as an average of numerous measurements) a diameter 

 of 0.10 ; in October, O.IG ; in l^Tovember, 0.18 to 0.23, while the eggs 

 showed other characters connected with approaching maturity which 

 earlier in the season were not to be seen. All the eels which were 

 captured later — in December and in January — part of which came from 

 rivers and harbors, part from the harbor of Putzig (Putziger Wiek) had 

 eggs measuring from 0.09 to O.OO™"", while, very exceptionally, some 

 measured 0.16™™, although among the fish examined were some which 

 measured 3 feet in length. 



XV Do MALE EELS LEAVE THE SEA AND ENTER I'RESH WATER. 



This problem is one of great interest, both to the biologist and the 

 fish culturist; it is, in fact, the one disputed point still remaining to be 

 solved. Upon its solution appears to depend the final decision of the 

 question, still so warmly debated both in Europe and America, "Do 

 eels breed in fresh water only, in salt water only, or in both fresh and 

 salt water?" As has already been stated, the theory for a long time 

 generally accepted is that the eels are " catadromous," descending to the 

 sea to spawn. This theory is, however, sharply contested by many observ- 

 ers, chief among whom on this side of the Atlantic is the Hon. Eobert 

 B. Roosevelt, President of the American Fish Culture Association. It 

 appears probable to the writer that the truth lies somewhere between 

 these two extremes, and that it will be hereafter ascertained that the 

 eel, like a majority of other animals, has flexible habits, sometimes devi- 

 ating from its ordinary custom, which appears to be to spawn in salt or 

 brackish water. 



Male eels have been found in the following localities : 

 (1.) In 1874, by Syrski, in the fish markets of Trieste, these markets 

 being supplied with eels from Chroggia on the Adriatic, and to 

 a lesser extent from the lagoons of Comacchio. 

 (2.) In 1875, on the coasts of France, by Dareste. 

 (3.) In 1875, among specimens of Anguilla mcmnorata from India. 

 (4.) In 1875, in the Baltic, at Wismar on the Danish coast, by Prof. 



Von Siebold. 

 (5.) In 1877, in the lagoons of Comacchio, by Jacoby. Among 1200 

 specimens, five per cent, were males; while among those less 

 than 15 inches in length 20 per cent were males. This was in 

 brackish water. (See paragraph XIX). 

 Bull. U. S. F. C, 81 7 



