of the Fishery Board for Scotland. 



391 



of other fishes. They are very rarely taken in the dredge, and yet are 

 numerous in their young state, as we have seen, when sought for in the 

 proper place — sheltered waters in the larninarian zone. Here they can 

 attach themselves to a floating frond, or dodge along among seaweed 

 capsules, confident in their colouring and their protective similarity. 



2. On the Multiple Tumours in Plaice and Flounders. By George 

 Sandeman, St. Andrews Marine Laboratory. (Plate XVII.) 



(Professor M'Intosh, in the Scottish Fishery Board's 

 Keport III. p. 66, & IV. p. 214.) 



The condition described in the above papers occurs in plaice and 

 flounders all the year round, but chiefly from March to November. 

 The fish affected have often an emaciated appearance, and seem to 

 be particularly liable to the attack of such parasites as Caligus. 

 The tumours occur quite irregularly on the fish : they may be situated 

 on any part, but are most common on the fins, and especially the pectoral 

 fin on the blind side. They consist of one or more cystic elements, often 

 occurring close to one another. An individual cyst is surrounded by a 

 hyaline membrane, and is in close connection with the inner surface of 

 the skin, which is always unbroken over it. The pearly-white sphere 

 has no deep attachment, but lies in loose connective tissue. On pressure 

 it bursts, and exudes a white, creamy, granular substance. On section 

 and microscopic examination these elements are seen to lie immediately 

 beneath the pigment-layer of the skin, which is often reflected round 

 them so as to nearly meet below. Their enclosing membrane is hyaline and 

 apparently structureless (Plate XVII. fig. 5.) but for a radial striation in 

 its inner layer, which gives it a close resemblance to an egg-membrane with 

 a zona radiata. The enclosed material is ' minutely granular, no distinct 

 ' cell elements being visible, though fine fibrillar occur throughout the field, 

 ' as if the fluid were coagulable.' It gives the staining reactions character- 

 istic of yolk. In PI. XVII. figs. 4 and 4a, may be seen one in which 

 development has reached what appears to be the nearly complete invest- 

 ment of the yolk by a blastoderm, as well as certain adjacent spaces in the 

 subcutaneous connective tissue, whence apparently other similar bodies 

 have escaped, leaving behind the hyaline investing membrane. These single 

 egg-like bodies occur frequently on the dorsal, caudal, and anal fins, being 

 usually situated between the fin rays, as well as to a less extent on the 

 dorsal and ventral surfaces. Frequently small depressions can be seen 

 which have been the seat of this condition, but there is never any mark 

 in the skin over the tumour while the body is still enclosed. 



The larger masses vary much in size and shape, ranging from a tumour 

 formed of two or three cysts to one of over an inch in length and half an 

 inch in diameter. They may be broad at the base, but are usually narrow 

 and projecting, sometimes appearing even pedunculated. They are more 

 common on the ventral surface than are the single elements, and are 

 specially frequent on the lower pectoral fin and lower operculum. They 

 have been found within the buccal cavity, on the edge of the vent, and 

 even extending a short way within. They can be seen through the skin, 

 which is he- e also perfectly normal, to be composed of separate spheres 

 (PI. XVII. fig. 1 ), though these assume the cuboidal or polygonal form 

 common where eggs are pressed together (PI. XVII. fig. 3). The elements 

 may be isolated, and appear in all respects like those described as occur- 



