194 SCIENCE PROGRESS 



emerging from the soil, is easily convinced of this contrast." 1 

 But one so naturally supposes that the distribution of life in 

 the sea is similar to that on the land that it is not easy to be 

 convinced that the opposite is really the case. The sea 

 temperature is highest at the tropics, and the intensity of 

 light is greatest there, so one might conclude that the conditions 

 of life would be more favourable in the equatorial zones. Then 

 everywhere in the tropical seas we find a greater variety of 

 species, and the animal forms are more brilliant in colour and 

 more ornamental in shape ; and one unconsciously confuses 

 this variety in form with abundance of individuals. Yet there 

 is no doubt that life in the polar and temperate seas is at 

 least as abundant as in the tropical areas. Wherever the 

 bottom-living invertebrate fauna has been sufficiently investi- 

 gated we find this to be the case, and some Arctic regions 

 show a bottom fauna which surpasses in abundance of indi- 

 viduals any other region which is known. The polar seas 

 are the chosen haunts of the marine mammalia, and these are 

 the largest animals which exist on the globe. The greatest 

 fisheries are those of the Arctic and temperate seas of higher 

 latitudes : I may give as instances the cod fishery of the sea 

 off the Lofoten Islands ; the fisheries round Iceland and 

 in the White Sea ; and the fisheries of the North Sea. All 

 this abundance of animal life is also indicative of a 

 corresponding wealth of planktonic life, and all experience 

 shows that this wealth exists. Probably the larger marine 

 algae are more varied in form and more abundant in the 

 temperate than in the tropical sea, and certainly this is the 

 case with the microscopic plants. In the Antarctic Ocean 

 there are ten and a half million square miles of sea bottom 

 which are covered almost exclusively with the dead shells of 

 diatoms. In both north and south polar seas great masses or 

 "banks" of living diatoms inhabit and discolour the surface 

 of the sea, and fishing operations are sometimes impeded by 

 this rank luxuriance of diatom life. Associated with this 

 abundance of vegetable life is the abundance of the other 

 planktonic forms which feed upon it ; thus vast shoals of 

 Pteropods inhabit the north temperate seas and the arctic 

 regions, and it is these that afford the food of the whales 



1 " Stoffwechsel im Meere," Wiss. Meeresunters. Kiel. Komm. Bd. 6, Kiel u. 

 Leipzig, 1902. 



