138 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



feet, or fractions of a meter, so that one may read oft' the depth to which the net 

 descends. By holding in the hand the tri-radiate support from which the net hangs 

 the latter may be kept from twisting on the supporting rope. 



In working, a spar is lashed to the upper deck of the steamer, so that its end 

 extends about 4 feet beyond the side of the vessel. To the end of the spar is lashed 

 a pulley, through which the net rope runs. The net is then allowed to sink. In going 

 down it takes in no water except that which is filtered through the gauze. It is 

 sometimes let to the bottom and sometimes to a depth of only 2, 4, or meters. It is 

 then drawn up by hauling in the rope hand over hand. The net is always hauled up 

 by the same person and note is made of the number of seconds between the time it 

 leaves the bottom and the time the top of the canvas cone reaches the surface. From 

 this time the velocity of the net is determined. The net is then drawn out of the 

 water and allowed to hang at the end of the spar while the water drains out of it. At 

 the same time a stream of water from a hose is turned upon the outside of the net. 

 This water is filtered in passing through the net gauze to the inside, so that it does 

 not add anything to the material captured in the net. The stream washes all the 

 plankton into the bucket beneath. 



After the water has partly drained out of the bucket, the binding screws are 

 loosened and the bucket is removed and taken into the cabin. Here nearly all the 

 water is allowed to drain out through the gauze sides of the bucket and the plankton 

 adhering to the inside is washed down into the conical bottom by means of a stream 

 of filtered water from a wash bottle. All the material taken in the net is thus collected 

 into the conical bottom of the bucket. A small glass beaker is then placed beneath 

 the tube in the bottom of the bucket, the plug is removed, and the plankton falls into 

 the beaker. The inside of the bucket and the plug are then rinsed several times in 

 filtered water and the rinsing water is added to the material in the beaker. The small 

 quantities of material obtained necessitates great care in handling lest some of it be 

 lost. The substitution of a plug in the bottom of the bucket for the stopcock used by 

 Apstein is believed to be an advantage, in that it allows the inside of the tube to be 

 rinsed with greater thoroughness. 



The small quantity of material now in the beaker contains very minute forms. If 

 this material be turned into a bottle of some fixing or killing fluid, and if this fluid be 

 afterward poured off and alcohol substituted for it, some part of the material is sure 

 to be poured oft' and lost. After much experimenting we finally hit upon the following 

 device for preserving the material: 



A .short 6-dram homeopathic vial has its bottom removed and edges annealed. 

 The bottom is then closed by tying over it with fine silk thread a piece of the No. 20 

 gauze, such as is used for the net. The contents of the beaker are poured into this 

 tube, and by gentle tapping the water is made to filter very rapidly through the gauze 

 bottom, leaving the plankton in the tube. Before all the water has filtered away a 

 label is placed in the tube and the open end is closed by tying over it a piece of the 

 gauze. The tube (see fig. 3) is then placed with other tubes in a large bottle of fixing 

 fluid. (We used alternately Flemming's solution and Kleinenberg's picro-sulphuric 

 acid.) The tube is then passed through successive grades of alcohol (preceded by water 

 in the case of the use of Flemming's solution), and is finally preserved in 82 per cent 

 alcohol. In passing the tube from one fluid to another it may be emptied of its fluid 



