42 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The transformation and growth of the larva. 



What conditions determine these processes ? Doubtless, 

 the relative abundance of food in the sea in a form suitable 

 for the nutritive organs of the baby plaice. Doubtless, also 

 the temperature of the sea, which will govern the rate of 

 assimilation. 



The food. 



The nature of the food is restricted since the organisms 

 eaten must be below a certain limit of size. There are many 

 pelagic organisms (animals and plants) that are small enough 

 so that there is usually a choice. Individual plaice exhibit 

 preferences. 



An account of the food of larval and post-larval plaice has 

 been prepared by Mr. A. Scott from collections made in the 

 Port Erin spawning pond. This is being published elsewhere. 



The variations in the abundance of the food. 



What are the ranges in the variations in abundance of 

 Diatoms, Peridinians and Copepods throughout a series of 

 years ? I hope to deal with this question soon, after the very 

 laborious task of collating the plankton estimates made by 

 Mr. Scott for the last fifteen years has been completed. The 

 conclusions may be applied to the data indicated above pro- 

 vided that we can be sure that the planktonic fauna and flora 

 of the spawning pond is similar to that of Port Erin Bay. 

 There are indications that it is similar and obviously it will 

 be an easy matter to apply tests. 



This discussion suggests that those fluctuations hi the 

 productivity of the fishing grounds that are to be deduced 

 from the official statistics are due to the variations in the 

 physical conditions that rule the abundance of food in the 

 sea. If in any one year an unusually large number of 

 eggs are spawned, or an unusually large number of eggs 

 develop and metamorphose successfully, there will be a rise 



