52 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The amount of material collected varied from 16 c.c. 

 to 28 c.c. Every haul was practically a gathering of 

 diatoms (Chcetoceros), with comparatively few Copepods 

 and other organisms. Another week later (October 4th) 

 Mr. Chadwick took a surface tow-netting in Port Erin 

 Bay, which revealed another complete change in the 

 plankton. The diatoms had almost entirely disappeared, 

 and a large number of Copepods, chiefly P seudocalanus 

 and Paracalanus, were then present. 



The distribution of the pelagic life in the sea is 

 influenced by many circumstances — winds, currents, sun- 

 shine and shadows, light and darkness, temperature and 

 salinity are important factors. These agencies at all 

 times have great effect in increasing or diminishing the 

 quantity and variety of organisms present. We know a 

 very great deal more regarding the distribution of certain 

 classes of pelagic and semi -pelagic organisms now than 

 we did a few years ago. For example, many Cope- 

 poda which were at one time regarded as strictly 

 limited to particular regions are now known to have 

 a very wide range. Every scientific expedition throws 

 fresh light on the subject. There are still quite 

 a number of such organisms whose known distribution 

 is very limited, but whether they will prove on further 

 investigation to be so local is very doubtful. A collection 

 of plankton taken by Dr. H. E. Eoaf this summer during 

 a traverse to Quebec and back, revealed some interesting 

 facts regarding the distribution of certain Copepoda, &c. 

 Calanus was represented in every gathering on the out- 

 ward journey, but the collections from mid-Atlantic 

 contained a much greater number of specimens than any 

 of the others. On the homeward traverse Calanus was 

 absent from one or two collections; again, however, the 

 mid-ocean gatherings contained the greatest quantity. 



