19 



There is a great deal of valuable material in those 

 statistics which, whether or not it leads to any definite 

 conclusions, will at least help us to see what further 

 observations are required, and what measure of success we 

 may hope to attain in the proposed census of the sea. 



Hatching Work at Piel. 



(Andrew Scott.) 



I. Fish Hatching. 



At the conclusion of the spawning season of 1898 it was 

 found that, in order to deal with large quantities of fish 

 eggs we should have to increase the capacity of our hatching 

 apparatus. After careful consideration it was decided that the 

 " Dannevig system," which has given satisfactory results in 

 Norway and in Scotland, should be adopted. This appar- 

 atus for incubating fish eggs consists of a series of movable 

 boxes, each of about a cubic foot in capacity, all floating 

 in separate compartments of a tank. The bottom of each 

 box is covered with fine silk gauze or hair cloth, the 

 meshes of which are of sufficient size to allow the water 

 to pass through freely and yet keep back the smallest size 

 of egg. Each box is placed in a separate water-tight 

 compartment, to one side of which it is hinged. The 

 water enters the box over a small shoot, and passes out 

 into the compartment through the perforated bottom and 

 then overflows into the next box. The apparatus is 

 constructed in sets, each set consisting of a double row of 

 five boxes in their compartments. At the ends of each 

 row there are smaller compartments, one at the top for 

 the distribution of the inflowing water, and one at the 

 bottom for collecting the waste, which is led away to the 

 nearest drain by an overflow pipe. The whole apparatus, 

 when placed in working order, is set on the floor at a 



