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Fart HI. — Thirteenth Animal Report 



between itself and the sides of the box. The first filter cloth, which 

 ought to be of a comparatively open material, is cut to the size of the 

 box, so that when put down it will cover the whole of the frame. Two 

 brass rods, introduced into a fold at the edge of the cloth, keep the filters 

 stretched in proper position, the rods passing outside the frame, and 

 resting in the space between the latter and the box. The frames are 

 placed with the netting below, and one above each cloth. When the 

 water passes, the filtering cloth is pressed against the netting on the 

 frame above it, to which the whole strain is transferred, and which keep 

 the cloths apart from one another. When the desired number of filters 

 are put in one over the other, the whole pile is tightly pressed down 

 against the fillets ; and all the joints being perfectly tight, the inflowing 

 water below the filters forces its way through them all, the outflow being 

 near the top of the box. As the water supply is taken either from the 

 pump directly or from the pond, it has pressure enough to pass through 

 all kind of filtering materials • several sheets of blanketing have 

 occasionally been used, and after the filtration the water is perfectly pure, 

 while its transparency before is perhaps a few feet only. The filters can 

 easily be taken out aud replaced with clean ones. It was found necessary 

 to use only one box in this way during the season, and when all the 

 hatching apparatus were working, the filters in this box only required to 

 be cleaned every six or eight hours in the most stormy weather, and 

 usually only once in twelve hours. 



In this way all difficulties regarding the hatching apparatus have been 

 overcome so far as the filtration of the water is concerned. When 

 sufficient pressure is available, any quantity can be obtained in the most 

 pure and satisfactory condition. 



The hatching operations were started on the 23rd of March and con- 

 tinued successfully to the last week in May, when the latest hatched fry 

 were put out. That the hatching work this year did not meet with 

 special difficulties from the exceptional conditions of the weather mentioned 

 above is chiefly due to the new method of filtration of the water. 



During the season 44,085,000 eggs were collected and 38,615,000 

 fry of plaice were transferred to various localities in the Firth of 

 Forth and St Andrews Bay. 



Besides the plaice, which was the principal species dealt with, 2,700,000 

 fry of cod were hatched and put out, and some hundred thousands of 

 haddock and whiting. The eggs of the two latter species were artificially 

 fertilised by Mr Liston while out on a trawler for spawning plaice, as 

 were also the eggs of the cod, except half a million, which I myself 

 fertilised at Dunbar. 



1. The Collection and Acclimatisation of the Spawners. 



During almost the whole season in 1894 some difficulty occurred with 

 the spawners in the pond. The majority of them had been caught during 

 the season, and a number placed in the spawning pond in a more or less 

 injured condition. A considerable number of those died, and the water in 

 the pond being deep, the bodies could not always be removed in time, a 

 circumstance which very much interfered with the regular spawning of 

 the healthy fishes. The total number of fishes in the pond, however, 

 was not very great and the supply of water was abundant, so that 

 the spawning continued till the fishes were spent ; but I saw that in 

 dealing with larger numbers it would be necessary to take precautions 

 to avoid such difficulties as far as possible. 



This year, therefore, it was intended to collect the fishes early enough 

 to have an opportunity to select the healthy and suitable fishes before the 



