SOUTHWELL: REPRODUCTION OF THE EEL. 219 



by Rathke, who in that year published an article in ' Miiller's Archiv' 

 on a female eel examined by him, ' the first and only specimen of a 

 pregnant eel which so far had been seen by a naturalist.' Dr. 

 Jacoby thus describes the ovaria of the eel which had been the 

 subject of so much controversy and which it had taken so many 

 centuries to discover, but which may be readily detected by following 

 his instructions. 



' If an eel be opened along its lower side from the breast to a 

 point behind the anus, there is seen besides the entrails and stomach, 

 and underneath the back part of the liver, the long swimming-bladder, 

 growing narrower towards both ends, and extending on one side as 

 far as the diaphragm, and on the other a little distance beyond the 

 anal opening. Along both sides of the swim-bladder there extends 

 a white or yellowish band, tolerably broad and shaped exactly like a 

 frill, whose inner edge is attached to the swim-bladder by a narrow 

 skin, a dupHcature of the inner skin of the abdomen, but whose 

 outer edge hangs down free in the abdominal cavity. Each of these 

 frill-like bands extends forward to the fore part of the fiver, passes 

 along the whole abdominal cavity, and ends a little distance back of 

 the anal opening, with which, however, it is in nowise connected. 

 In these bands, which contain a great deal of fat, numberless eggs are 

 embedded. By tearing a little piece of this band with a pin and 

 carefully wiping off the small drops of fat, one can recognise the eggs 

 with the naked eye as very small white dots. The microscope, however, 

 will distinctly reveal their form and inner construction. . . . The 

 fact that it took several centuries of eager search to discover these 

 ovaria is, to some extent at least, explained by the circumstance that 

 up to the present day all attempts to discover larger and more 

 developed eel-eggs have- proved futile. It is well known that there 

 were no good microscopes till about thirty years ago. Even the eel 

 which was examined by Rathke, the only pregnant eel which has 

 been found, although its distended ovaria filled the whole abdominal 

 cavity, contained only very small eggs, the largest measuring 

 o. I millimetre in diameter. Larger eel-eggs, on the point of cutting 

 loose from the ovaria and turning to young eels, have still to be 

 discovered.' 



Hitherto reference has only been made to the ovaria of the eel, but 

 the history of the researches for the male organs of this singular fish 

 are not less interesting, although very recent. It was not till the year 

 1842 that any decided opinion as to the sexual organ of the male eel 

 appeared ; in that year Hohnbaum-Hornschuch, in a dissertation on 

 the sex and generation of the eel, came to the conclusion that the eel 

 was hermaphrodite. In 1871 three celebrated anatomists, — first 



May 1885. 



