S Fishery Board fur Scotland. 



19 and 38, although small, is functional and readily seen, while in 

 Fig. .40 the testi.s is so much reduced as to be probably non -functional, 

 and might be easily passed over. In the last ovary old egg-capsules 

 were present, the remains of a previous spawning. The two classes of 

 reproductive organs differ also in the amount of empty space in the 

 early developing ovary {cp. Figs. 42 and 45). 



Three sections were made across the organ shown in Fig. 40, viz., 

 at the points A, B, and C. The point A is near the anterior ex- 

 tremity : the section is given in Fig. 45. The testis is visible as a 

 little projecting fold : the oviduct is absent. No part of the wall of 

 the ovary is free from eggs, but the ridges are narrow on the dorsal 

 and ventral sides. In a section at B, viz., across the beginning of the 

 oviduct, Fig. 46, the oviducal part is very narrow internally ; there is 

 little, if any, clear space. The testis is flush with the outer skin. The 

 ovar}^ has a big lumen. In the posterior part of the ovary at C, the 

 oviduct is broader ; the testis is a little fold (Fig. 47). Near the union 

 of the ovaries, viz., at D, the outside breadth of the oviduct is not 

 equalled by plain surface on the inside. The plain surface of the 

 oviduct inside an ovary is shown in Fig. 23. It exhibits a quantity 

 of minute white granules, which are thickly arranged about the 

 middle and gradually get fewer towards the egg-ridges at the sides. 

 Minute muscle-fibres are visible in the wall. 



In the small ovarj', Fig. 38, which is probably ripening for the first 

 time, the oviduct can be traced further anteriorly than in Fig. 40 (cp. 

 the cross sections, Figs. 42 and 43). 



A section across the union of the ovaries of another fish shows the 

 posterior end of the septum (Fig. 49). In this case the testes were 

 dorso-lateral in position, while in another example the}" were ventro- 

 laterally placed. At a short distance posterior to the above point. 

 Fig. 50, the wall of the oviduct was spongy, thick, extensile, all round 

 except at the ventral region.* The testis was present on one side onlj*. 



The oviduct is wider than in the male. On the last part of the 

 oviduct I observed two lacunar areas, one bigger than the other, with 

 intervening plain areas, which exhibited straight longitudinal fibres. 



The external opening of the oviduct is large ; the lijDS are some- 

 times broad and leaf-like. 



The urogenital papilla in the female is small. The opening on its 

 tip is crater-like, and on first examination it appears to be a single 

 aperture. But if a section be made across the papilla the two ducts 

 are found. The urethra has a thick wall, and its lumen diminishes 

 somewhat near the aperture. The vas deferens is a slit which is 

 closed (Fig. 41). The two ducts meet just at the aperture. The 

 papilla is formed of spongy material. 



It is an interesting problem whether a fish which becomes unisexual 

 will remain alwaj^s of that sex. It seems probable that it will do so, 

 for in several developing predominant females I have found the old 

 capsules of ripe eggs which had been retained in the spent ovary. 

 (Firfealso p. 10.) 



Notes on the Reproductive Organs. 



The stage of development of the ovary in the fishes examined in 

 each month is indicated by the size of the eggs entered in the last 

 column of the table on page 4. 



