56 



Hoffmann, moreover, tried to ascertaiu whether the young fishes, 

 which the fishermen of the Zuiderzee are accustomed to call 

 »zeebliek" (a kind of whitebait), are indeed young herrings or 

 not. He corapared the number of rays of the pectoral, ventral , 

 dorsal and anal fins, the number of keeled scales between the 

 ventral and anal fins of the little fishes with those of the full- 

 grown herrings, and comes to the eonclusion that what is called 

 »zeebliek", is nothing else but young herring. As these young 

 herrings are taken in the Zuiderzee throughout the whole year 

 there is good reason to believe that the young herrings stay in 

 the Zuiderzee during the first year of their existence, 



Hoffmann's coutributions to the knowledge of the life-history 

 of the herring , the principal fish of the Zuiderzee , have proved 

 very valuable in many regards ; I tried also to augment that 

 knowledge, but chose another way to attain the end I wished. 

 I almost entirely omitted to rear the young herrings artifici- 

 ally , and tried to find in the open sea the material neces- 

 sary for the study of the development of this fish, and was 

 fortunate enough to collect all the stages I wanted. Before 

 giving the results of my own studies, I wish, however, to point 

 out that the investigations of KupfFer ^) and Hoffmann have been 

 highly profitable to my own researches. I hardly believe that 

 without these »Vorstudien" 1 should have been successfull in work- 

 ing out this part of ray task. 



The first time I got a mature female herring in the Zuider- 

 zee was on 9 April 1888. The slightest pressure was sufficiënt 

 to cause the eggs to come out of the genital pore. The weight 

 of the fish was 125 gram., that of the spawn 27.5 gram. The 

 colour of the spawn was no longer yellow but rather reddish ; the 

 eggs were diaphanous like glass. On April 17 I got agaiu quite 

 mature herrings ; there were numerous female and also a few male 

 specimens: the fluid milt as well as the eggs came out of the 



i) Kupffer, Jahresber. d. Comm. z. Unters. d. Deutschen Meere. IV — VI. 1878. 



