A RTIFICIAL HA TCHING OF MARINE FOOD-FISHES. 259 



the mortality being thus very serious. In the instance of 

 forty-three millions of ova sent by rail from Gloucester 

 station, only one hundred and fifty thousand larvae were 

 forthcoming for liberation. The same species of flounder as 

 in the preceding season gave four million six hundred and 

 eighty-nine thousand seven hundred ova between February 

 and March, from which issued three million three hundred 

 and fifty thousand eight hundred larval fishes. 



At Gloucester marine station in 1889-90, forty millions 

 of the ova of the pollack produced fourteen millions of 

 larvae. From forty-seven millions of the eggs of the cod 

 fourteen millions of larvae were obtained ; while from thirty 

 millions of the eggs of the haddock, only five millions of 

 larvae were liberated. No statistics are given for 1890-91, 

 except that thirty millions of the eggs of the cod collected 

 in the neighbourhood, and, therefore, favourably situated, 

 gave 25*5 percent, of larvae. 



At Dunbar, the ova are voluntarily shed in the spawning- 

 pond, which is forty and a half feet long by eleven feet 

 two inches deep, the breadth varying from twenty-six and 

 a half feet at the one end to eighteen feet at the other, and 

 into which clean sea-water is sent in a full stream from a 

 three-inch pipe of galvanised iron. The current carries 

 them to a trough called the spawn-collector, which at 

 first had only a frame of horse-hair cloth, but the eggs 

 are now more expeditiously collected by a fine gauze bag 

 through which the water passes, and which only requires 

 to be gently inverted into a suitable vessel of sea-water to 

 secure the eggs in perfect condition. Before collecting the 

 eggs for the day, a larger current is made to pass out of the 

 pond, thus increasing the number of eggs in the collector. 

 The ova are measured and counted, and then placed in the 

 hatching-boxes, each of which has the same length and 

 depth, viz., eleven and a half inches, and ten and three- 

 quarter inches brOad, while the bottom is of hair- 

 cloth. 



The boxes are attached by leather hinges to the parti- 

 tions, and when the troughs are full of water the free end 

 rises until it projects about three inches above the water, 



