372 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



AN INTENSIVE STUDY OE THE MARINE 

 PLANKTON AROUND THE SOUTH END OE 

 THE ISLE OF MAN.— PART VI. 



By W. A. Herdman, F.R.S., Andrew Scott, A.L.S., 

 and H. Mabel Lewis, B.A. 



(With a plate and other illustrations.) 



METHODS. 



This work has been continued during 1912 on the 

 same general plan as in preceding years. This completes 

 the sixth year of this collection and detailed analysis of 

 the plankton week by week, and we consider it desirable 

 that, if possible, ten years of continuous observations 

 should be accumulated before any change is made in the 

 scheme of work. That, it is hoped, may enable us to 

 draw conclusions which are not vitiated by the data of 

 some exceptional year. 



The work at sea in April, 1912, during the time of 

 the vernal phytoplankton, was carried on from the steam- 

 yacht " Runa," with the capable assistance of Mr. W. 

 Riddell and his successor, Mr. H. G. Jackson; while in 

 Port Erin Bay Mr. Chadwick and Mr. T. N. Cregeen, 

 of the Biological Station, collected six samples a week 

 throughout the year — two with a fine net (No. 20 silk), 

 two with a coarse one (No. 9 silk), and two vertical hauls 

 from 5 fathoms. The authors have divided the rest of the 

 work between them on the same general lines as in 

 previous years. 



As in the case of the last report, we shall give here 

 only a comparatively brief statement of results, selecting 

 for discussion any points which seem new or which we 



