[13] SCIENTIFIC EXAMINATION OF THE GERMAN SEAS. 537 



fastened at the back two rows of gristly gill-leaflets (Fig. IV, B), which 

 are covered with so thin a skin that in the live fish they look dark red 

 from the blood passing through them. 



*o Tig. TV.— The arch of a gill of the herring (natural s ; ze). 



A, leaves of the pills (blood red in live fish) ; B, arch 

 of the trills ; C, gill-rakers or slender appendages on the 

 anterior border of the arch. 



Fig. V. — The gills of a herring (natural size). 





PlQ. 



- ft 



.a 



s s 





A, arch of the gills; B, the anterior border of the 

 gills, garnished with the rows of gill-rakers ; C. leaves 

 of the gills. The tube protruding between the four 

 rows of leaves is the beginning of the oesophagus. 



In front the f ICt . Yl.—Part of the arch 



arches of the gills %*£&1*£S? 



have a dense row 



of slender append- 



ages, technically 



called gill-rakers, 



on each side of 



them (Fig. IV, C; 



Fig. V, B, and Fig. 



VI, C.) All water 

 which the herring takes in its mouth to let it flow 

 out again over the gills in breathing must pass 

 through the fine grating formed by these spinous 

 points. By this process all small animals which, 

 with the water, enter the mouth and gill-cavity are 

 retained in it, and accumulate till they are swallowed. 



' A, leaves of the gills 



This enables the herring, whenever the water is (Wood red in the live fish) ; 



07 B, part of the arch of the 



full of small life, to fill its stomach in a short time puis ; c, giii -rakers covered 



• -• _ . „__ T , with small spines. 



with thousands of them. In February, 1872, 1 found 

 in the stomach of one herring 15,000 small crustaceans, in another 

 19,000, and in a third one even 60,000. These small crustaceans are only 

 about 1 millimeter long. Fig. VII shows one of these crustaceans mag 



