of the Fishery Board for Scotland. 



225 



where friction with the wood on the bottom of the spawning pond had 

 evidently occurred — probably in the preliminary movements during pro- 

 gression ; and the fact that spaces of about f of an inch existed between 

 the planks, thus presenting sharp angles, may have increased the liability 

 to injury. While the plaice did not suffer in this way, the heavier turbot 

 after a time did. These patches of ulceration, which readily healed when 

 the fishes were removed to the enclosed creek, however, cannot be held 

 to be the sole cause of the arrest of spawning. Round and Hat fishes 

 labouring under grave tumours and other affections, just as in the 

 higher forms of animals, spawn freely, and extensive distortion 

 of the spine in the cod and other fishes, also as in the higher 

 forms, is no bar to complete fecundity. Ripe flat fishes in confinement are 

 prone to a disease, which may in common language be termed " egg- 

 bound," — that is to say, though they have pure sea- water, a certain space, 

 the presence of males and abundant food, yet they refuse to shed their 

 eggs. This condition, indeed, was specially referred to in the case of the 

 flounder at St Andrews Marine Laboratory, in the Third Annual Report of 

 the Board.* Though the ovaries are enormously distended with ripe eggs, 

 or eggs that have been ripe, occlusion of the ducts by spasm or otherwise 

 prevents their issue, and in some instances leads to the death of the adult. 

 In the ovaries of the female turbot at Dunbar, degeneration had already 

 taken place to a considerable extent on the 7th September. In the centre 

 of the enlarged ovary was a large space filled with glairy mucus, contain- 

 ing degenerating ova, which had formerly been ripe. The mucus was 

 mixed with fatty debris and granules with shrunken egg-capsules. The 

 fishes were evidently getting rid of the eggs of the season, chiefly by dis- 

 integration, while in the walls of the ovary a crop of minute eggs were 

 developing in a healthy condition. The turbot sheds a considerable 

 quantity of ripe eggs at a given time, as, for instance, when landed on the 

 deck of a ship, but in the ripe turbot confined at Dunbar, it required 

 gentle, though steady, pressure, continued for some time, before the stream 

 of ripe eggs issued, and thus they are in contrast with many flat fishes. 

 Muscular spasm was evidently the cause of the retention of the ripe eggs. 

 Some might be inclined to urge that it is useless to experiment with such 

 fishes as the turbot and the sole, which spawn in deep water, and which 

 require this great pressure (of water) to aid them in discharging their eggs. 

 They would argue also that such fishes have a slow rate of spawning, and 

 that there is no great pressure of ripe eggs in the ovary. Unfortunately, 

 pressure, even to rupture, in the ovaries of such as the flounder, on the 

 one hand, will not force the eggs outward, and on the other, the deep- 

 water theory is effectually disposed of by the fact that the soles spawn in 

 the tanks of the Plymouth Laboratory. 



As already mentioned, the turbot recovered from the ulcers when they 

 were removed to the enclosed creek having sand on the bottom, and, more- 

 over, they lived there throughout the severe winter till April, thus show- 

 iug remarkable vitality under the circumstances, especially when it is 

 remembered that the creek was at this time somewhat overcrowded. 



The following was the condition of the ovaries of five examples taken 

 at random in the beginning of April. 



1. Length of adult, 27 \ inches. The interior of each ovary formed a 

 chamber, the rugose walls of which were covered with degenerating eggs — 

 wrinkled, collapsed, and opaque — the contents in each egg consisting of 

 minute granules of yolk and various oil-globules, which, by transmitted 

 light, had a slightly yellowish colour. In most, the capsule had ruptured 

 and permitted the contents to escape. The wall of each ovary consisted 

 of rugose laminae, chiefly longitudinal, in the elongated posterior legiou, 



* 1885, p, 62. 



