88 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



organs of reproduction in the descriptions hitherto given of them, I in- 

 tend to commence by describing these organs, first, with the view of 

 rectifying and completing the details, and also for the purpose of com- 

 parison with the male organs. 



The ovaries of the eel. — These organs (tig. IG), two in number, are rib- 

 bon-shaped, with leaflets on their outer face, and with transverse folds. 

 In the natural position of the live fish, the one extends to the left and 

 the other to the right of the alimentary tube, following most of its angles 

 nearly the whole length of the abdominal cavity to the place where the 

 dorsal i^arietes is confluent with the lateral. 



The right ovary commences at a point nearly corresftonding to that 

 ■where on the outside the right pectoral fin ends, and the left ovary com- 

 mences about two centimeters and ends three to four centimeters behind 

 the former. They extend three to six centimeters back of the anus, 

 into the caudal part of the animal's body ; they do not, however, unite 

 in a single body, as some have asserted, but both are toward the end 

 inclosed in a peritoneal membrane, and are separated from each other 

 by the union of these membranes, having each on their inner face an ac- 

 cessory ovary {]^ars recurrens ovarii). In rare cases is such an accessory 

 ovary wanting either on the right or on the left side. 



The ovaries in fully-grown eels are in the middle about two centimeters 

 larger, and i)osteriorly terminate in a thread-like form. They are not 

 smooth on both sides, but have, as was said above, on their outer side 

 numerous transverse folds (fig. 2) full of eggs (fig. 3). 



It is another of Eathke's erroneous assertions, likewise maintained 

 by others, that the genital opening through which the eggs pass out 

 from the abdominal cavity is formed by two holes, a right one and a left 

 one. I have invariably found in all specimens examined a simj)le hole, 

 which communicated with the right and left half of the abdominal cav- 

 ity by means of a transverse fissure between the straight intestine and 

 the urinary bladder [fissura recto-vesicalis) and opens in the urethra 



(fig- 4). 



It is generally admitted that the eggs, when loosened from the ova- 

 ries, fall indiscriminately into the abdominal cavity, but it is not said 

 which way they take in order to go out through the genital aperture. 

 As I have invariably found that the fully-developed ovaries lean with 

 their outer surface against the side of the abdominal cavity, and approach 

 with their free edges the lower portion of this side, forming, so to speak, 

 a furrow, I must conclude that the loosened eggs descend between the 

 abdominal j)artition and the folds and leaflets of the ovary in the above- 

 mentioned furrow, and from it pass to the genital aperture without 

 scattering in the abdominal cavity. 



As to the development which the ovaries undergo, I have observed, 

 from the end of November till the beginning of March, in many adult 

 eels, of the length of 530 millimeters and more, that the ovaries were of 

 the breadth of 15 to 25 millimeters, and of a yellowish and sometimes 



