6 Fishery Board for Scotland. 



provender from the blood supply. The kidney was found to be 

 infected with the same parasite, and at the same time the spinal 

 nerves were laden with the cysts of G 'aster osiomum gracilescens. The 

 cj^sts of this trematode when present in the skin of the whiting are 

 surrounded by black pigment,* and thereby give the skin a spotted 

 appearance. Gamble and Drew state that this condition is due to the 

 presence of a trematode, probably Holodomum cuticola, v. Nordmann, 

 which causes a similar infection in German cyprinoids. Some of 

 the cysts measured *5- - 6 mm. in length. In order to discover how 

 far this dual infection occurred, 27 spotted haddocks f were examined. 

 In 26 of these the parasite was found in both muscles and kidney, 

 and Gasterostomum gracilescens cysts were present in the nerves. 

 In the remaining fish the condition in the kidney was not noted, but 

 the muscle and nerves were infected by the respective parasites. 



In the kidney the cysts were generally smaller than in the muscles, 

 and they were attached to a green thallus-like body (th., figs. 19, 173). 

 The cyst in fig. 19 measured, from x to y, '6 mm. The thallus 

 has a structure : it is not a smooth plasma. It is amber-coloured, 

 and it has scattered through it dark brown bodies (b., figs. 173, 174). 

 These dark brown bodies are also to be seen out in the tissue of the 

 kidney apart from the cyst (fig. 33) ; they measure roughly about 

 *01 and less in diameter. 



The branched parasite is shown in figs. 18 and 174. In the latter 

 case it consists of seven branches. From other cysts, three and four 

 larvse are found to have wandered (figs. 24 and 30). In fig. 177 fifteen 

 branches (a. larvee) are seen, but their relation to one another was not 

 definitely made out. The larva in the kidnejr measured practically 

 the same size as those in the muscles, viz., "12 mm. No. 2 in fig. 30 

 (larva a., fig. 177) measured "12 mm. in length, while p., fig. 19, was 1 

 mm. long. A little branched form is shown in fig. 23. It was found 

 detached and a little distance away from fig. 24. 



The " thallus " varies in size. A comparatively large one is shown 

 in fig. 173. It measured about '25 mm. in length. The cyst is 

 attached to the thallus and is probably deriving sustenance from it. 

 This cyst in greatest diameter measured # 12 mm. The spindle- 

 shaped bodies (cr.) present in the thallus, and also in the kidne}^ tissue, 

 are, I think, crystals. The cyst is thick- walled and contains five 

 chambers at least. Two of these are empty (e. ch.) The wrinkles in 

 the envelope assume a very characteristic form (cp., fig. 21). In some 

 cases the thallus had no cyst attached, e.g., th, th', ih", fig. 30. In 

 this drawing a larva (2) is seen to have arrived (?) at a thallus, viz., 

 th 7 . In some cases there is only one chamber visible in the cyst, 

 (figs. 24 and 34). It is possible that the walls of the chambers may 

 have collapsed. 



The kidney tissue does not appear to be broken up near the 

 parasite ; still, the more the kidney is infected the more fluid it appears 

 to become. There are some small amber-coloured centres filled with 

 greenish amber corpuscles. 



Little green corpuscles were observed in the kidney tissue (g., fig. 

 32); b. in the same figure, is a dark brown body. 



A little green thallus with a capsule attached was observed in the 

 muscles also. 



* Williamson, H.C.— "Notes on the Eggs of Angler, etc." 

 t Mr. Geo. Angus kindly supplied some of these fishes. 



