Methods in Plankton Investigations. 



«i> ' 



inserted upon the shoulder. The shrinking of the tube as it 

 cools holds the bottom firmly in place, and it can then be 

 completed as shown in Fig. 3. At the center of the bottom 

 is the outlet of the bucket, which is reamed to hold the taper- 

 ing plug {p.). Both the plug and the bottom are finished 

 obliquely to a drip-point (d. p.) at one side. This facilitates 

 the removal of the last few drops of the catch from the bucket. 

 The bucket below the bottom of the windows holds about 

 7 cu. cm. The base (ba.) retains the original thickness 

 (.5 cm.) and its weight adds to the stability of the bucket. 

 Since the drip-point does not project below the base the 

 bucket can be set down, and, owing to the fact that its center 

 of gravity is low, it is not easily overturned. This is a dis- 

 tinct advantage where the work must be done in a small row- 

 boat at the mercy of the waves. 



The band clamp (Plate II., Fig. 4 and 5, b. c.) is a sheet 

 of brass 4.5x15.3 cm., and about .1 cm. in thickness. At 

 a distance of .75 cm. from the ends the sheet is bent out at 

 right angles, and a brass bar 4.5 X. 75 X. 25 cm. is soldered 

 in the angle thus formed (Plate II., Fig. 4 and 5, pi. and//.'). 

 The band is now bent around the bucket and the ends brought 

 together by means of two screws (sc.) which pass through 

 the one bar and screw into the other (Plate II., Fig. 5, pi. 

 and //.')• The windows (Fig. 4, w.) can now be cut through 

 both the band and the walls of the bucket. The pillar (Fig. 

 5, pi.) between the windows adjacent to the ends of the clamp 

 is .5 cm. wider than the other pillars, whose width is about 

 1 cm. The inner edges of the windows are carefully rounded 

 so as to afford no lodgment for the plankton. It is also a 

 convenience to attach the band of silk (Fig. 4, s.) which closes 

 the windows to the side of the bucket by means of a thin 

 coat of King's waterproof cement. The band clamp can then 

 be slipped over the bucket and the silk bound firmly in place 

 by tightening the two screws (Fig. 4 and 5, sc). The base 

 also bears an eye (e.) for the line which fastens the bucket to 

 the carriage at z (Plate III., Fig. 6). 



The above-described detachable bucket, devised by the 

 writer, has certain obvious advantages over the Apstein and 



