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FOUNDERS OF OCEANOGRAPHY 



The following, showing a sudden change in the nature of 

 the plankton, is quoted from one of the Port Erin Plankton 

 Reports : — 



" We were fortunate enough on one occasion to obtain 

 incontrovertible evidence of the sharply defined nature of a 

 shoal of organisms, forming an instructive example of how 

 nets hauled under similar circumstances a short distance 

 apart, may give very different results. On the evening of 

 April 1 (1907), at the ' alongshore ' Station III, north of 

 Port Erin, one mile out, I took six simultaneous gatherings 

 in both surface and deeper waters. Two of the nets were 

 the exactly similar surface tow-nets called A and B. At 

 half-time I hauled in A, emptied the contents into a jar, and 

 promptly put the net out again. This half -gathering was of 

 very ordinary character, containing a few Copepoda, some 

 Diatoms and some larvse, but no Crab Zoeas. At the end of the 

 fifteen minutes, when all the nets were hauled onboard, all the 

 gatherings, includiug A, showed an extraordinary number of 

 Crab Zoeas (Plate XX, Fig. 1), rendering the ends of the nets 

 quite dark in colour. A was practically the same as B, although 

 A had only been fishing for seven minutes. It was evident 

 that at about half-time the nets had encountered a remark- 

 able swarm of organisms which had multipHed several times 

 the bulk of the catch and had introduced a new animal in 



