190 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



interest to many people in Liverpool and the neighbour- 

 hood, but that it led to a more general diffusion of useful 

 information as to the objects of our Sea-Fisheries Com- 

 mittee and as to its methods of work. It is only in 

 this way, and by courses of public lectures, that we can 

 hope to secure a wider knowledge and appreciation of 

 fisheries work, of the object of regulations, and the value 

 of scientific investigation. The Catalogue of the Sea- 

 Fisheries Exhibition, as arranged in Liverpool, is appended 

 to this report. 



" Plankton " Investigation. 



. One of the most important determining factors in the 

 distribution and movements of fish is clearly their food. 

 In past reports we have given a considerable amount of 

 information of the same kind as has been given elsewhere 

 by other fishery investigators, as to the more or less fixed 

 food derived from the sea bottom in the case of most of 

 our common edible fishes. We are now making a more 

 systematic study than has yet been done in this district 

 of the floating and drifting fish food found in the surface 

 and deeper layers of water throughout the sea, and which 

 is coming to be called "plankton." Much of the plankton 

 consists of microscopic plants and animals which are, 

 throughout their life, in a free condition. But another 

 important constituent is the enormous quantity of eggs, 

 embryos, and larval stages of many animals which, in 

 the adult condition, are to be found on the sea bottom. 

 These young stages are most of them only to be found at 

 certain times of the year, and consequently the plankton 

 differs considerably, both in nature and amount, according 

 to the season, and also, to some extent, according to the 

 weather. As the plankton is liable to be moved about 

 from place to place by tidal and other currents, by pre- 



