MIGRATIONS OF THE EEL. 649 



Do MALE EELS LEAVE THE SEA AND ENTER FRESH 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 remain- 

 ing to bo 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 observers, chief among whom on this side of the 

 Atlantic is Hon. Robert B. Roosevelt, president of the American Fish Cultural 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 deviating 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 Chioggia 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 marmorata from India. 



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



(5) In 1877, in the lagoons of Comacchio, by Jacoby. Among twelve hundred specimens, five 

 per cent, were males; while among those less than fifteen inches in length twenty per cent, were 

 males. This was in brackish water. 



(6) Iii 1879, at Trieste, by Dr. Hertnes, who found fifteen males among twenty Eels selected 

 by Dr. Syrski. 



(7) In 1880, on the Baltic coasts of Denmark, by Dr. Hermes. Out of one lot of thirty-six 

 from Wismar, he obtained eight males, thus repeating von Siebold's observation. 



(8) In 1880, from the Baltic between Zealand and Saland, Denmark. Out of one lot of thirty- 

 six, Dr. Hermes obtained eight males. 



(9) In 1880, in France, by Robin. 



(10) In 18SO, by Cattie. 



(11) In 1S80, by Dr. Hermes, at Cumlosen, on the Elbe, about one hundred and twenty miles 

 from the German Ocean. 



(12) Iii 1880, at Riigers on the Baltic, by Dr. Hermes, who found forty-four and one-half per 

 cent, males in one lot of 137. 



(l.'l) By Dr. Pauly, among Eels planted at Hiiningen, in Alsace-Lorraine. 



It lias been shown by Dr. Pauly that among the very young Eels [Montfa] taken near the 

 mouths of rivers is a considerable percentage of males, which, when transplanted to fresh water, 

 will there retain their masculine characters and develop into perfect adult males. This discovery 

 is, of course, of the utmost importance to tish-culturists making the attempt to introduce Eels into 

 new waters. Its importance has already been pointed out by Director Haack. 



The practical lesson to be learned is simply this, that young Eels, for introduction into 

 strange waters, must be taken from very near the mouths of rivers, in order that both males and 

 females may be secured. The interest to zoologists lies in the fact that Pauly's discovery renders 

 the theory of von Siebold less plausible, indicating that the sexes of the young Eels are differ- 

 entiated before they begin to mount the rivers anil that the males do not ascend beyond the limits 

 of brackish water. 



