74 TRAXSACTIOXS LIVERPOOL BIOLOGICAL SOCIETY. 



prevalent winds, shelter, depth of water, nature of 

 bottom and condition of the shell-fish bed, all affect the 

 distribution of the sewage and other organisms; and the 

 Bacteriologist who undertakes such work, unless he is a 

 Field-Naturalist and Fisheries expert and knows how to 

 allow for the various factors in the environment, runs 

 considerable risk of being deceived by the samples 

 examined and of arri\ing at erroneous concliLsions as to 

 the condition of the shell-fish in relation to sewage 

 contamination. 



Plankton iNVESTiciATioNS. 



Mr. Riddell and I have undertaken for a second year 

 a discussion of the plankton samples which I collected 

 from my yacht in the seas to the North and West of our 

 district. This year our cruise in July and August 

 extended from the Irish Sea to the Shetland Islands, so 

 we were able to sample undoubted Atlantic water of high 

 salinity bringing in Oceanic organisms. The relations 

 of the Oceanic water and its living contents to the periodic 

 changes and variations in the plankton of our coastal 

 waters are not easy to unravel, and our occasional 

 collecting expeditions to the Scottish waters north of this 

 district are undertaken in the hope of throwing light on 

 the distril)ution of the [)laiiktoii organisms and their 

 history tliroughout tlie year. 



My investigations, with Mr. Audrc^w Scott, of the 

 plankton collected in the Irish Sea throughout the year 

 have followed the usual lines and are reported upon in 

 " Intensive vStudy," Part V, in the same manner as 

 before. I'he work is of such a detailed nature tliat no 

 brief statement iii regard to it can b(> usefullv made. 



