NORTH ATLANTIC PLANKTON. 35 



belonging to the Allan Line, I was permitted to make 

 arrangements for running sea-water through my silk 

 tow-nets continuously, day and night, daring the voyage 

 from Liverpool to Quebec early in August, and back 

 from Quebec to Liverpool at the end of September (fig. 1) . 

 The method adopted was the "pump " one, by which 

 the nets are not immersed iri the sea, but -are merely 

 used to strain the organisms from the sea-water which has 

 been pumped into the ship. My nets were made of the 

 best silk bolting-cloth, known technically as grit-gauze, 

 and I used the following four lands : — 



Net A, 82 meshes to the inch. 



Net B, 72 meshes to the inch. 



Net C, 80 meshes to the inch. 



Net D, 172 meshes to the inch. 



On the port side of the ship I was allowed to have 

 complete command of a large tap on the main deck, near 

 the galley. This brought sea- water from a large tank in 





Fig. 2. —Rough diagram -to show positions of tap, overflow pipe, jitc* 



