

[5] PROPAGATION OP THE EEL. 461 



Mr. Dallmer regarding the occurrence of eels in the sea, more especially 

 in the North Sea: "Eels are found in the North Sea wherever there are 

 islands and banks, even if these are left dry at low tide, but in the open 

 sea they are never found. On the west coast of the island of Sylt, which 

 is not obstructed by banks, no eels have, to my knowledge, ever been 

 caught, whilst a great many are caught on the west coast of the 

 island of Amrum (only a few miles distant), which is protected by a num- 

 ber of banks. Near Heligoland eels are frequently caught, a line and 

 hook to which a stone is tied being thrown into the sea from the shore. 

 Beyond the turbid yellowish water surrounding the island no eels are 

 caught. Near Nemverk, on the Watt, I have caught many eels, but I 

 feel convinced that beyond a line drawn from Gross-Vogelsand to Schar- 

 horn no eels can be found. I am therefore of opinion that it may be con- 

 sidered absolutely certain that the Watten Sea, and the mouths or the 

 lower parts of rivers, and not the open North Sea, are the spawning 

 places of eels." Such observations of practical fishermen, based on 

 accurate knowledge and experience, are exceedingly valuable, and it 

 is to be desired that a larger number of similar observations could be 

 made and published. 



Among the outward signs by which a male eel may be recognized is 

 a very striking metallic or bronze color, by which it can easily be dis- 

 tinguished from the female. Mr. Hinkelmann could thereby always 

 beforehand inform me how many males I would find among the fish 

 which he sent me. Among these there were several which measured 

 45 centimeters in length. 



For a further study of the eel question it will be necessary to continue 

 these investigations in as many rivers, bays, and coast waters as possible. 

 Every one interested in this matter is herewith requested to send me 

 eels. They are best packed in wicker baskets in moist sea-weeds or 

 aquatic plants. I presume that in view of the general interest felt in 

 this matter the German Fishery Association will gladly bear the ex- 

 penses. 



EXPLANATION OF THE ILLUSTRATIONS. 



A. Fully matured male sexual organs — one-half the natural size — of a sea eel (Conger 



vulgaris) measuring 74 centimeters in length. 



a, stomach ; d', upper; d", middle; d'", lower part of the liver folded back; 

 /, swimming-bladder; g, gall-bladder; h, anus ; il, i2, i3, i4, the different 

 parts of the left testicle ; fcl, k2, fc3, k4, hb, the five parts of the right testi- 

 cle; I, Bursa seminalis; m, urinary bladder; p, skinny border of the testi- 

 cles. 



B. Spermatozoids. 



C. Undeveloped sexual organs (ovaria) — one-half the natural size — of a female sea eel 



Conger vulgaris) measuring 84 centimeters in length. 



a, stomach ; i, ccecum ; c, spleen ; d, liver ; e, right ovarfcim ; e', left ova- 

 rium;/, swimming-bladder; g, gall-bladder; h, anus; m, urinary-bladder; 

 p, base of the left ovarium. 



