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Part III. — Thirteenth Annual Report 



III. — ON THE REPRODUCTION OF THE EEL. By H. Charles 

 Williamson, M.A., B.Sc, Marine Laboratory, St Andrews. 



It is intended in this paper to briefly review the work which has 

 been done within the past few years, in connection with the life-history 

 of the eel. 



The eel is, in most countries, considered an important food-fish, and 

 in many places large revenues are derived from the eel-fisheries. In 

 Scotland the eel is not regarded with favour as an article of diet. Large 

 consignments of eels are, however, sent from Scotland to English markets. 

 Various methods are used for the capture of this fish, the principal 

 apparatus being the eel-trap. Eel-fishing is usually most prolific in the 

 autumn, when the eels migrate to the sea. In certain places they are, 

 at this time, captured by means of nets. 



A very complete history of the eel question was published by Jacoby 

 in 1880. He traces the different stages of the opinion of scientific men 

 regarding the unsolved problem of the reproduction of the eel. The 

 fact that the sexes were separate was not demonstrated until 1874, when 

 Syrski described the organ which is now known by his name, and 

 which is most probably the testis of the eel. The fresh impetus given 

 by the discovery of the lobe-organ by Syrski, has resulted in a very 

 extensive increase in the knowledge of the habits of this form. In this 

 country and on the Continent the species of eel which has been under 

 observation is Anguilla vulgaris ; in the United States Anguilla boston- 

 iensis has been studied. According to Giinther these two species 

 differ in the following points. In Anguilla vulgaris the length of the 

 head is nearly equal to the distance between the commencements of 

 the dorsal and anal fins, and is less than one-half of its distance from 

 the vent, while in Anguilla bostoniensis the length of the head is 

 conspicuously more than the distance between the commencement of 

 the dorsal and anal fins, and is contained twice and one-half in its 

 distance from the vent. Of the many varieties of the common eel, 

 Giinther considers Anguilla latirostris alone worthy of specific rank. 



The following account of several points connected with the life-history 

 of the eel is almost wholly drawn from the many articles in the subject. 

 Observations made at this Laboratory, are, however, also included. It 

 is proposed to deal first with the reproductive organs of both sexes, and 

 subsequently with the autumn and spring migrations, &c. 



The Female Reproductive Organs. 



The ovary of the eel was first described by Mondini in 1777, and in- 

 dependently, three years later by O. F. Miiller. In 1850 the first mature 

 eel which had come under observation was examined by Rathke. The 

 ovaries of the eel consist of two frill-like bands extending the whole 

 length of the abdominal cavity, from the liver to beyond the anus. 

 Each ovary is attached by its dorsal or adherent edge to the peritoneal 

 covering of the swim-bladder and the upper part of the abdominal 

 wall ; its ventral border is free. The colour of the ovary varies according 

 to the stage of development of the eel. In young eels 28*7 cm. (1 1*5 

 inches) long, the ovary is glassy in appearance, with a very slight whitish 

 tinge ; in larger eels the ovaries, crowded as they are with eggs and fat 

 spaces, are opaque and white in colour. 



