44 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



study, but it requires to be systematised and extended. We 

 have made some small contributions to portions of it in the 

 past in our own reports, and work of a similar nature is seen 

 in the Clare Island Survey, article " Marine Ecology " by 

 R. Southern (1915), in Sumner's " Intensive Study of the 

 Fauna," etc., in Bulletin of the Bureau of Fisheries for 1908, 

 in Orton's " Contribution to an Evaluation of the Sea," etc. 

 (M.B.A. Journal, 1914), and in my " Spolia Runiana IV " 

 (Linnean Journal, 1920). But the earliest, most important 

 and most complete investigation is that of Dr. C. G. Joh. 

 Petersen and his assistants in the Reports of the Danish 

 Biological Station for some years back, and especially the 

 Report for 1918. He uses a bottom-sampler, or grab, which 

 can be lowered down open and then closed on the bottom so 

 as to bring up a sample square foot or square metre (or in 

 deep water one-tenth of a square metre) of the sand or mud 

 and its inhabitants. With this apparatus, modified in size 

 and weight for different depths and bottoms, Petersen and his 

 fellow- workers have made a very thorough examination of the 

 Danish waters, and have arrived at certain numerical results 

 as to the quantity of animals in the Kattegat expressed in 

 tons, and have shown the dependence of all these animals, 

 directly or indirectly, upon the great beds of Zostera in the 

 Kattegat. Such estimates are obviously of great biological 

 interest and, even if only rough approximations, are a valuable 

 contribution to our understanding of the metabolism of the 

 sea, and of the possibility of increasing the yield of local fisheries. 

 It seems probable that the estimates of relative and absolute 

 abundance of such organisms may be very different in different 

 seas under different conditions. The work will have to be 

 done in each great area, such as the North Sea, the English 

 Channel, and the Irish Sea, independently. This is a necessary 

 investigation, both biological and physical, which lies before 

 the oceanographers of the future, upon the results of which 



