GERMAN PLANKTON INVESTIGATIONS. 



283 



The Vertical Net. 



The large vertical plankton net consists essentially of 

 three parts : — 1. The conical head piece (Fig. 1, A). 2. The 

 net itself, B ; and 3, a metal cylinder or bucket suspended 

 at the apex of the net, C. 





Fig. i. 



The newest form of the net is here described, and the 

 description therefore differs in some details from that given 

 by Hensen (1). 



The head piece consists of a circular iron ring 1 , e, of 

 38 cm. diameter, so that the area of the mouth of the net is 



