6 Fishery Board for Scotland. 



This drawing- represents a transverse section of a portion of a testis. 

 The tubules, which are ari-anged in a columnar form, are in some 

 cases branched, and they appear to connect directly with the series of 

 ducts occupying the core of the lobe. Each tubule is enclosed at the 

 surface of the testis in a loculus formed by partitions arising from the 

 outside wall {sic, Fig. 10). The skin of the testis wdien torn tends to 

 split longitudinally. 



Some testes were mottled. The yellow mottling is seen in the core 

 of the testis ((int., Fig. 24). May this mottling indicate that the fish 

 has spawned before ? 



The egg-ridges vanish in the posterior part of the ovary, which 

 becomes the plain-walled oviduct (Fig, 39). This figure represents a 

 view of the two organs in a predominating female. The ovaries are 

 large, and the testes {T) are very small. On the side of the ovai*y next 

 the wall of the abdomen there is a digitiform region of the wall of the 

 ovary without egg-ridges. It is the oviduct (ovd.). 

 The testes do not unite. 



The general arrangement of the organs in the abdomen of a 

 predominating male is shown in Fig. 6. The external aperture of 

 the vas deferens is omitted. 



A series of transverse sections, not drawn to scale, illustrate the 

 arrangement of the parts. Fig. 24 is a section of a functional male 

 organ near its anterior end. The ovary has only a small attachment 

 to the testis. A section made near the junction of the ovaries exhibits 

 a similar condition (Fig, 25), Large lacunae are visible in the wall of 

 the ovary. Egg-ridges are present, but not on the portion of the wall 

 next the lacunae. In a section further posteriorly, but where the 

 ovaries are still separate (Fig.- 26), the lacunar tissue in the wall of the 

 ovary is very extensive. Ova are present on part of the wall of the 

 ovary. The testis had alread}^ ended at this point. A small lobe was, 

 however, found in a section of the single oviduct (Fig. 27) posterior 

 to the union of the ovaries. The junction of the ovaries is shown in 

 Fig. 28. In the section of the oviduct (Fig. 27), the lacunar tissue in 

 its wall represents the two vasa deferentia, which it was not possible 

 to separate. The lacunar tissue is apparentl}' present throughout all 

 the wall of the oviduct. Further posteriorly the lacunar tissue is very 

 much increased (Fig. 32). It is present in the whole of the Avail of 

 the oviduct, the mesentery forming a break or division. The lacunar 

 tissue was broader on one side than on the other, but that may be 

 simply due to unequal contraction. The strands which form the net- 

 work of the lacunar cavities appear to be muscular. A surface view 

 of the inside of the last portion of the oviduct is showm in Fig. 35, 

 The duct has been slit open along its dorsal (i.e., posterior) side. The 

 lacunar tissue can be seen in parts through the lining skin of the 

 oviduct. It has a different appearance in different parts. 



Near the end of the oviduct the lacunar tissue (la.) forms very 

 large cavities (Fig. 33) on the dorsal side, and in a section made close 

 to the external aperture, ie., next the ventral wall of the abdomen, 

 spaces are seen to have grown into a definite tube on the dorsal edge, 

 the vas deferens (VD,, Fig, 34). The posterior mesentery cuts the 

 lacunar tissue into two. 



The further relationship of the parts is shown in a longitudinal 

 section through the cloacal region (Fig. 31). It is shown upside down. 

 The lacunar tissue on the posterior side is seen to open out into a 



