Methods iii Plankton Investigations. 2o 



Fi<;. 9. — Rim of cover of net, showing clamp for holding cover in 

 place. X 1. 



c Clamp, in position. i. w. Inner wall of trough. 



c'. Clamp, released. o. to Outer wall of trough. 



coo. Cover. str. Strap of clamp. 



/. Foo.t of cover. w. Wing of cover. 



Fie. 10. — Same, showing method of fastening outer silk net; cover 

 partially removed. X 1. 



//. I. Butchers' linen. o. n. Outer net. 



cd. Cord. 

 Other lettering as in Figure 9. 



Plate V. 

 The plankton pump. X iV 



Plate VI. 

 The plankton pump in operation. 



Plate VII. 

 The centrifugal machine. X J^. 



