198 



Part III. — Thirteenth Annual Report 



mass of the ova are of uniform diameter, there are usually a few smaller 

 eggs present. In the case of the eels 25^ and 20f inches long, the 

 greater number of the ova had a diameter of *135 mm., but some eggs 

 were as small as -09 mm. in diameter ; and so with other specimens 

 recorded in the table above. The larger eggs, from * 18-27 mm. in 

 diameter, show a large spherical mass of oil globulea, which occupies 

 almost all the space within the zona. When the egg is examined in the 

 fresh condition the nucleus is not seen, owing to its being obscured by 

 this collection of oil globules. 



The Male Reproductive Organs. 



"What is undoubtedly the testis of the eel was first described by Syrski 

 in 1874, under the name of 'lobe-organ.' No observer * has, so far, found 

 ripe spermatozoa in the lobe organ of Syrski, but the histological examina- 

 tion of the lobes made by several zoologists have shown that this organ 

 exhibits a minute structure, similar to that found in the immature testis of 

 other fishes. The discovery of spermatozoa, also, in the homologous organ 

 of the Conger, by Dr Hermes, f affords conclusive proof of the testicular 

 nature of the lobe-organ. The testis occupies in the body of the male a 

 position corresponding exactly to that of the ovary in the female. It is 

 formed of a large number of separate flattened lobes, convex on their 

 internal surface, and on their external surface plane or slightly concave. 

 Each lobe is attached by its base to the vas deferens ; its free border is 

 rounded at the corners. The testis begins in the anterior part of the 

 abdominal cavity, and ends at some distance behind the anus, in a prolonga- 

 tion of the abdominal cavity. It is attached in its whole extent by the 

 vas deferens to the peritoneal lining of the superior part of the abdominal 

 wall, and occupies a position alongside the swim bladder. The vasa 

 deferentia, from the abdominal and caudal portions of the testis on each 

 side, open into a triangular-shaped cavity, which occupies a position 

 between the rectum and urinary bladder. This cavity opens, by the 

 genital orifice, into the ureter, and by the latter to the cloaca. The left 

 testis begins a short distance behind the right testis, and extends a little 

 further into the caudal region than the right. The lobes receive their 

 blood supply from the testicular artery which runs parallel with and close 

 to the vas deferens ; the blood is returned to the testicular vein, which 

 occupies a position alongside the testicular artery. 



In a male eel, 12^f inches (320 mm.) in length, examined at St 

 Andrews, it was found that the right testis commenced at a point 12 mm. 

 behind the diaphragm, and 16'5 mm. from the insertion of the pectoral 

 fin. The portion of the testis within the abdominal cavity, that is, as far 

 back as the anus, was 7'9 cm. in length, and consisted of 41 lobes. The 

 caudal portion was 16 mm. long, giving a total length to the right testis 

 of 9*5 cm. On the inner surface of the caudal portion there was an 

 accessory testis (pars recurrens testis). The pars recurrens testis was 

 described by Syrski. Robin, however, states that he failed to find a pars 

 recurrens to either testis. The pars recurrens of the right testis began at 

 a point 4 '5 mm. from the posterior extremity of the testis, and extended 

 forward for a distance of 7*5 mm. 



The lobes of the anterior portion of the right testis had a breadth of 

 1 5 mm. The lobes decreased in width as they approached the anus, at 



* Kingsley, however, was of the opinion that, on tearing a portion of a testis, he 

 saw spermatozoa with independent motion. American Naturalist, vol. xiii. , 1879. 



t Hermes, 1 On the Mature Male Organs of the Conger,' Bulletin U.S. Fish. Comm., 

 1881. 



