. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. POSSIBLE IMPROVEMENTS 5°i PLANKTON [ W///////W//////////////////////77T,) A • H A H It would be a great advantage to be able to use two grades of gauze, one of coarse mesh for the zooplankton and one of much finer mesh for the phytoplankton. Attempts using a ribbon of fine-mesh gauze sewn on to the coarser gauze to entrap the smaller phytoplankton forms have not proved successful. It is hoped later to construct a miniature auxiliary water tunnel which could be fixed to the body of the standard m
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. POSSIBLE IMPROVEMENTS 5°i PLANKTON [ W///////W//////////////////////77T,) A • H A H It would be a great advantage to be able to use two grades of gauze, one of coarse mesh for the zooplankton and one of much finer mesh for the phytoplankton. Attempts using a ribbon of fine-mesh gauze sewn on to the coarser gauze to entrap the smaller phytoplankton forms have not proved successful. It is hoped later to construct a miniature auxiliary water tunnel which could be fixed to the body of the standard machine, so that a narrow very fine-mesh gauze within it could be wound on at the same rate as the gauze in the main re- corder ; it would be worked by an extension from the main driving gears. Alternatively the main water tunnel could be divided by a vertical partition to separate a narrow tunnel leading to a fine-mesh gauze placed side by side with the coarser gauze, the two fabrics winding on together into the formalin tank. The front opening of the small tunnel could be reduced to a mere £ in. sq. to allow for the greatly reduced filtration with the fine-mesh gauze. In the Type I machine with a larger opening a grid of intersecting wires was placed at the front opening to prevent large objects entering the water tunnel; in the Type II machine with the very much smaller opening the grid was dispensed with. Recently two records have been spoiled by pieces of fish, evidently struck off by the nose of the machine, entering the water tunnel and jamming against the slit for the exit of the gauze. It is proposed to reintroduce a pro- tective grid at the front opening. A series of vertical vanes might be fixed within the water tunnel to prevent the tendency of the plankton to be carried more to one side of the gauze than the other on account of the slightly asymmetrical path of the water tunnel (see p. 468). My colleague, Mr C. E. Lucas, has suggested a modification of the machi
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