CONSIDERATION OF INDIVIDUAL FISH loi 



or 2aII, i.e. 607 per cent, and eleven tables gave some other formula, 

 i.e. 39'3 per cent."- 



Other investigators have endeavoured to apply Heincke's methods 

 to the differentiation of herring races. Some, e.g. Matthews,* say 

 the method is inapplicable to the herring samples they examined ; 

 others, e.g. Hoek, claim successful results. The establishment of 

 morphological differences between various herring races, if, indeed, 

 such differences exist, is a task to be undertaken by future in- 

 vestigators. 



In a recent paper, Williamson* summarises the methods of in- 

 vestigation into the races of European herring. He discusses the 

 characters on which emphasis should be laid in distinguishing 

 different races of herring, insisting on the necessity of having a 

 uniform list of characters for use by all investigators. Reference 

 should be made to this paper, which gives one an idea of the diffi- 

 culties of the problem of distinguishing herring races. 



An interesting account of the results obtained by the study of 

 the scales is contained in papers published by the Norwegian 

 scientists, Hjort and Lea. It is claimed that the scales furnish the 

 best means of determining the age of a fish like the herring. Seen 

 under the microscope, a herring scale is divided by a transverse 

 line into two entirely different parts. One part is very transparent 

 and exhibits no special peculiarity, whereas the other and posterior 

 part is striated, and has a number of concentric transparent semi- 

 circular zones, each bounded by a dark line. The investigations 

 prove that the dark, narrow rings are formed in winter, and are 

 consequently called winter-rings ; whereas the broad transparent 

 zones are summer growths. A zone and a ring constitute a year's 

 growth, and consequently from their number the age of the fish 

 can be determined. 



Scale of Herring — 29 cm. in length. 



1 For further criticism see Jenkins, " The difference between spring and autumn 

 herring," Trans. Biol. Soc, Liverpool, Vol. XVII, 1903. 



2 " Report as to the Variety among the Herrings of the Scottish coast," dth and 

 5th Ann. Rep. Scots. Fish. Bd., 1885 and 1886 ; 4th, p. 61-98 and 5th, p. 295-316. 



» A short r&um6 of the researches into the European races of herrings and the 

 method of investigation. Fisheries, Scotland, Sci. Invest, 1914, I (April 1914) 



