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AUG 1895 

 The Reproductive Maturity of the Common Eel. 



By 

 J. T. Cunningham, M.A. 



In the Museum of the Eoyal College of Surgeons, in London, there are 

 two specimens of the common eel, in which the ovaries are much 

 enlarged, greatly distending the abdomen, and evidently very nearly 

 ripe. Both those specimens were presented by Mr. Geo. Buckeridge, 

 a salesman in Billingsgate Market, who deals largely in eels. The 

 following are certain particulars concerning the specimens : — 



(1) Length 15 in., weight 4J oz. Presented Jan. 4, 1894. 



(2) Length 19 in., girth round the abdomen 5|in., weight 10^ oz. 

 Presented Sept. 25, 1895. 



Both specimens are in spirit, mounted for exhibition, and the ovaries 

 are seen to be of opaque milk-white colour, and generally to present the 

 same appearance as the nearly-ripe ovaries of the Conger described by 

 me in Vol. IL of this Journal. The greatest width of the ovaries is 

 1^ in. or 4'8 cm. The eggs are scarcely visible as distinct grains to the 

 naked eye. Microscopically examined in a small piece which Professor 

 Stewart kindly gave me from the larger specimen, the largest eggs 

 were found to be from "13 to '16 mm. in diameter, while the smallest 

 were only "07 mm. It is a remarkable fact that eggs considerably 

 larger than this have been found in the unripe ovaries of eels in the 

 ordinary condition. Mr. Williamson (Thirtcetith Anmial Rep. of 

 Scottish Fishery Board, 1895) states that in a specimen 707 cm. long 

 (28iin.), some of the eggs measured '27 mm., and several other observers 

 have given the maximum size as '25 mm. In the ripe specimen 

 described by Eathke, in 1850, the eggs were also small, not exceeding 

 *2 mm. In the specimen here under description, the microscope showed 

 that the ovarian lamellae were composed almost entirely of ova in close 

 apposition, the adipose tissue so plentiful in the ordinary condition of the 

 ovary having been absorbed. It should be remembered that the eggs 

 were measured after preservation in spirit, which must have caused 

 contraction ; but Eathke, who examined his specimen when it was 

 fresh, also remarks that the eggs were distinctly smaller than in 

 eels with small ovaries. 



NKW .SEKIKS. — VOL. IV. NO. 2. H 



