of the Fishery Board for Scotland. 



219 



floating just above the bottom in Kiel harbour, from October 1885 to 

 February 1886. He examined the reproductive glands of the eels at 

 intervals of eight to fourteen days. The eggs did not increase in size ; 

 they retained the diameter of 0 215 mm., which they already had in 

 October. In the testes of the male eels he found no spermatozoa. 



As to the return of the eels from the sea, authors are divided in opinion. 

 While the bulk of the evidence seems to point to the return of the 

 migratory eel to fresh water, still additional proof is required to make that 

 contention final. On the other hand, the statement that the eel dies from 

 exhaustion immediately after the reproductive act, is supported by very 

 few facts ; and these facts have only an indirect bearing on the question. 

 Another view is held by some zoologists, viz., that the eel which has 

 migrated to the sea never returns to fresh water, but remains in the sea. 



Blanchard * suggests, as a means of finding out the life-history of the 

 eefin salt water, the labelling of a large number of migrating eels. He 

 is of the opinion that the eels never return to fresh water. • It is known,' 

 he says, ' that in the Salmon Fisheries of Scotland and Ireland, the life- 

 ' history of the salmon has been learned by attaching to a large number 

 ' of specimens labels by which they may be recognised on their return 

 ' from the sea. It would be necessary, when the large eels descend the 

 ' water courses to return to the sea, to capture numerous individuals at all 

 1 points on our shores, and to attach to these little metallic labels, and 

 ' then to set them at liberty. In all probability it would happen that 

 ' some labelled specimens would be re fished after a sojourn in the sea of 

 ' some months or a year, and these specimens bearing the mark of their 

 ' origin would enlighten us regarding a phenomena, as yet remaining 

 ' without demonstration. There is in the knowledge of the complete life- 

 1 history of the eel a scientific question of very great interest, on economic 

 ' question of perhaps great importance.' 



Conclusion. 



We must, in conclusion, admit that, notwithstanding the fact that 

 time and attention has been ungrudgingly devoted to this question by many 

 eminent zoologists, we know really nothing concerning the most important 

 point connected with the life-history of the eel, as it is of every animal, 

 viz. its reproduction. The whole question rests upon the problem, how 

 to capture the eels after they have entered the sea. When we consider 

 that the eel may without difficulty travel a very considerable distance 

 from the coast, and when we remember that spawning is supposed to take 

 place in winter, a season during which an examination of the sea-bottorn 

 could be made only under very great disadvantages, it is at once apparent 

 that a problem of great difficulty remains for solution. 



I beg to acknowledge my indebtedness to Professor M'Intosh and Dr 

 Fulton for much assistance with the literature of the subject. 



* Blanchard, ' ^Itude de TAnguille de riviere apres son passage de l'eau douce 

 4 dans les eaux salees,' Comptes Rcndus Ac. Sc. Paris, t. 109, 1889. 



