104 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the first fertilised eggs were placed in the hatching boxes for 

 incubation. This is about three weeks earlier than in 1912, and 

 is the earliest spawning that has taken place in our tanks.* 

 The last eggs were collected on April 24th. The spawning was 

 therefore completed in eight weeks. During that period one 

 and a quarter millions of plaice eggs were collected, and thirteen 

 and a half millions of flounder eggs. The eggs were incubated 

 in the usual manner and the resulting fry were liberated from 

 time to time. The adult fish were also liberated at the end of 

 the work. The experiment of marking the adults before libera- 

 tion, which, had been done in 1912, was not repeated, as none 

 were returned to us. 



The following tables give the number of eggs collected, 

 and of the fry hatched and set free on the dates specified : — 





Plaice (Pleuronectes platessa, Linn.). 









I 



jggs Collected. 



Fry Set Free. 







Feb. 



27 



.. 20,000 



16,000 ... 



March 



20 



March 2 



.. 35,000 



30,000 ... 



j> 



25 



>> 



4 



.. 45,000 



39,000 ... 



>> 



>» 



?> 



7 



.. 55,000 



46,500 ... 



j> 



31 



>> 



9 



.. 65,000 



57,000 ... 



>> 



> > 



>> 



11 



.. 70,000 



60,000 ... 



>> 



55 



T> 



13 



.. 75,000 



65,500 ... 



April 



7 



>> 



15 



.. 80,000 



69,000 ... 



> ? 



,, 



J> 



18 



.. 80,000 



69,000 ... 



5> 



14 



J> 



21 



.. 90,000 



79,000 ... 



>> 



55 





24 



.. 95,000 



84,000 ... 



>> 



21 



>> 



27 



.. 90,000 



79,000 ... 



)> 



,, 



J> 



31 



.. 90,000 



79,000 ... 



>> 



28 



April 



4 



.. 85,000 



74,000 ... 



S> 



it 



> » 



8 



.. 85,000 



74,000 ... 



May 



5 



>> 



12 



.. 75,000 



65,500 ... 



>» 



,, 



>> 



16 



. 55,000 



46,500 ... 



>> 



14 





20 



.. 40,000 



33,000 ... 



> > 



>> 



» 



24 

 >tal Eggs 



.. 25,000 



20,000 ... 



Fry. 



>> 



Tc 



1,255,000 



1,086,000 Total 





*It is curious that at the Port Erin Fish Hatchery the Plaice spawn 

 a good deal earlier than at Piel. This year the first fertilised plaice eggs 

 were obtained in the Port Erin pond on February 4th. — W.A.H. 



