160 



A CENSUS OF THE SEA 



[part II 



vertical sample of plankton can hardly be expected to vary within 

 the limits of such a column. The following table gives the results 

 of four hauls taken at stations 2 and 3 in the North Sea^. I have 

 simplified the table from those given by Apstein. 



Principal Plankton j)resent in the North Sea {German Stations 2 

 and 3) in a column of water 1 square metre in cross section. 



Now these figures represent the results of four typical plankton 

 catches and will give the reader an idea of the nature and abun- 

 dance of microscopic life in the sea — as revealed by the employment 

 of silk bolting cloth, No. 20, as a filtering medium. Many 

 different genera and species of diatoms, protozoa (chiefly peridinians), 

 copepods, &c., were obtained, but I have grouped all these to- 

 gether and the reader who is curious will find the detailed lists 

 in Apstein's Tables. It will be seen that the diatoms, peridinians 

 and copepods are the most abundant organisms in the sea and that 

 one or more millions of some of these things may be contained in 

 a column of sea-water about 40 metres, or less, in height, and one 



1 Lat. 55° 40' N,, Long. 3° 30' E. is the mean position of the stations. 

 are situated on the N.E. of the Dogger Bank. 



They 



