[15] 



SCIENTIFIC EXAMINATION OF THE GERMAN SEAS. 



539 



the stomach (Fig. XI, D), at whose back there are hollow tubes (Fig. VIII 

 and Fig. XI, E) which, when food is plentiful, are filled with a fatty juice. 

 In front of the stomach there is a short and wide cavity (Fig. XI, F). 



Fig. XI. — Entrails of the herring. 



A, intestinal canal; B, air-passage between stomach and swimming-bladder; C, gills; D, stomach; E, 

 appendages of the stomach ; F, oesophagus; G, swimming-bladder. 



From the stomach a tube, the pneumatic duct (Fig. XI, B), passes to the 

 swimming-bladder (Fig. VIII and Fig. XI, G), which shines like silver, 

 and has the shape of a spindle. On either side of the swimming-bladder 

 are the kidneys (Fig. I, X), and between these and close below the spine 

 there is a large blood-vessel (Fig. I, B) in which a large portion of the 

 blood which has passed through the gills is conveyed to the lower part 

 of the body. 



2. — ON THE DIFFERENCES BETWEEN THE SEA-HERRING AND THE 



COAST-HERRING. 



The opinion that the herrings come to our shores Irom the northern 

 seas, and that all which are not either devoured by other fish or are 

 caught by fishermen return to those seas after the spawning season is 

 over, cannot be correct, because the different parts of the ocean are in- 

 habited by herrings differing in shape and size. 



The herrings which are caught in the Xorth Sea and in the Baltic have 

 grown up in those seas. They may be divided into two varieties, the 

 coast-herring and the sea-herring. The coast-herring of the Baltic 

 spawns in spring in the shallow coast waters, where the bottom is cov- 

 ered with a rich vegetation. The sea-herring spawns in deep water, and 

 its principal habitation is the Xorth Sea. The sea-herring of the Baltic 

 spawns at a depth of 4 to 5 meters. 



Sea-herrings only make their appearance a short time before the 

 spawning season, as migratory fish, coming in dense schools, and soon 

 afterwards disappear again. 



Coast-herrings, on the other hand, stay near the coast all the year 

 round, in greater or smaller numbers. In placing a coast-herring by the 

 side of a sea-herring (both being of the same length), the fore part of the 

 body of the sea-herring appears longer and more slender (Fig. XII) than 



