FOREIGN RESEARCH ORGANISATIONS 139 



one-fifth to one-half of that of a similar fertile 

 and cultivated land-surface. In the meantime, the 

 general investigation of the economic fauna of the 

 sea was also commenced, and such subjects as the 

 reproduction and food of fishes were investigated. 

 The work on the herring, carried out about this 

 time (1878), is very noteworthy. KupfFer and 

 others investigated the natural history and embry- 

 ology of this fish, and Heincke, in several papers 

 in the Jahresberichte and in two colossal volumes ^ 

 published by the Deutsche See-Fischerei Verein, 

 made a most exhaustive study of the variability of 

 the morphological characters of the herring, which 

 has resulted in the demolition of the migration 

 theory long held. This work greatly extended 

 our knowledge of this important food-fish, and 

 supplemented in a considerable degree the earlier 

 work of the Scottish Fishery Board. Following 

 these, a number of papers on general fisheries 

 subjects have' appeared, and a most fertile and 

 original line of research was instituted by Hensen 

 and his pupils — the quantitative determination of 

 the fish-population of the sea, and of the planktonic 

 organisms which form the ultimate food-material 

 of these animals. I shall refer to this work later 

 on, and in the meantime only notice it as one of 

 the most remarkable and suggestive studies which 

 has hitherto been made in marine biology. 



1 Naturgeschichte des Herings, Abhandlungen Deutschen See-Fisck. 

 Ver., Bd. ii. Hefte 1-2, 1898. 



