110 Part III. — Twenty -fourth Annual Report 



then passes on to the hatching apparatus. These are 22 in numoer, and 

 are of the Dannevig pattern. They are shown in fig. 1, pi. VII., which is a 

 view of the inside of one end of the hatchery. The apparatus on each 

 side are supplied by separate pipes. 



The pump-house is contiguous to the hatchery room, and opens into it. 

 It is provided with three Worthington direct-acting steam pumps, specially 

 made for use with sea water, and brass lined. They are shown in fig. 2, 

 pi. VII. They are so fitted up that any one of them, or all together, can 

 be used to pump water from the filter-chamber, either to the reservoir or 

 to the pond ; there are two suction pipes, one for the large pump and one 

 for the two smaller pumps. Steam is supplied by an upright donkey 

 boiler, with two tubes, which is fitted with an injector and pump, but the 

 town water supply can be used direct, the working pressure being usually 

 401bs. The pump-house measures 18 feet 10 inches by 15 feet; its 

 position is shown at b in fig. 1, pi. VI. 



The tank-house, which is used in connection with the scientific 

 researches at the laboratory, is built partly over one end of the large 

 spawning pond (fig. 2 c, pi. VI.), and there is a platform along this side 

 over the pond. It is provided with, six concrete tanks, four of which 

 have plate glass in front and back, and the other two plate-glass fronts 

 only. The latter are 6 feet -4 inches long, 4 feet 3 inches deep, and 3 J feet- 

 high ; the others are 5^ feet in length, the other dimensions being the same 

 as in the larger tanks. These tanks may also be used for experiments with 

 fresh- water fishes if desired, fresh water pipes being fitted up to them. A 

 bench runs along one side and one end of the tank-house, provided with 

 a central leaden gutter, and suitably sloped, and pipes are carried over it 

 to supply either sea water or fresh water to small tanks aad dishes. 



The various operations in connection with the work at the hatchery 

 have been described in previous reports. Here it may be enough to say 

 that the adult living plaice, from which the spawn is procured, are kept 

 in the large spawning pond from year to year, their food consisting chiefly 

 of mussels. The plaice which die are removed from the pond as soon as 

 observed, and a fresh stock to replace those lost in this way is obtained 

 each autumn by sending the attendant out on trawlers working inshore, 

 who brings them in in tubs through which a current of water is 

 maintained. 



When spawning begins, the eggs float in the water of the spawning 

 pond, from which they are removed by a large net of mosquito netting, 

 which is towed around the pond for an hour or so each day as a rule. 



The eggs are then transferred to the hatching boxes, which receive a 

 supply, as copious as possible, of clean filtered sea water, until hatching 

 occurs ; and when the larvae have nearly, but not quite, absorbed the 

 yolk they are transferred to the sea in suitable localities. 



The cost of the hatching work is small. The scientific investigations 

 carried on at the laboratory require that water should be pumped regularly 

 to supply the tanks, dishes, and apparatus in the tank-house, and some- 

 times in the hatching room, and the only additional expense incurred in 

 connection with the hatching work is for extra coal while the work is 

 going on, for the assistance of a boy to help the attendant during the 

 busiest weeks, and for the hire of boats to put out the fry. The total 

 cost is estimated at under £100. 



The hatchery has been of great advantage in connection with the 

 demonstrations to fishermen from the coast of Scotland, who come each 

 spring to the laboratory for this purpose. It forms a great attraction to 

 them, and enables them to form useful conceptions as to what goes on 

 naturally in the sea with respect to the reproduction of fishes, as well as 

 furnishing them with specimens for the study of their development. As 



