268 FOUNDERS OF OCEANOGRAPHY 



1. The sequence of stages in its life-history — such as the 

 Nauplius and Cypris stages of Balanus. 



2. The results of interaction with other organisms — as 

 when a swarm of Calanus is pursued and devoured by a 

 shoal of herring. 



3. AbnormaHties in time or abundance due to the physical 

 environment — as in favourable or unfavourable seasons. 

 And these factors must be at work in the open ocean as well 

 as in coastal waters. 



Then, turning to other problems, let us take next the fact 

 — if it be a fact — that the genial warm waters of the tropics 

 support a less abundant plankton than the cold polar seas. 

 The statement has been made and supported by some 

 investigators and disputed by others, both on a certain 

 amount of evidence. This is possibly a case like some other 

 scientific controversies where both sides are partly in the 

 right, or right under certain conditions. At any rate there 

 are marked exceptions to the generalization. The German 

 Plankton Expedition in 1889 showed in its results that much 

 larger hauls of plankton per unit volume of water were 

 obtained in the temperate North and South Atlantic than 

 in the tropics between, and that the warm Sargasso Sea had 

 a remarkably scanty microflora. Other investigators have 

 since reported more or less similar results. Lohmann found 

 the Mediterranean plankton to be less abundant than that 

 of the Baltic, gatherings brought back from tropical seas 

 are frequently very scanty, and enormous hauls on the other 

 hand have been recorded from Arctic and Antarctic seas. 

 There is no doubt about the large gatherings obtained in 

 northern waters. I have myself in a few minutes' haul of 

 a small horizontal net in the north of Norway collected a 

 mass of the large Copepod Calanus finmarchicus sufficient to 

 be cooked and eaten Hke potted shrimps by half a dozen of 

 the yacht's company, and I have obtained similar large 

 hauls in the cold Labrador current near Newfoundland. 



On the other hand, Kofoid and Alexander Agassiz have 



