100 



THE SEA FISHERIES 



much more unlike one another than one of them is unlike a group 

 of autumn herring to which Heincke's formula 2al applies. 



This difference may theoreticaUy be very great, as may be seen 

 on reference to the following table :— 



Formula. 



2bII. Spring herring 

 2al. Autumn herring 



In every respect the second group of spring herring is more like 

 the autumn herring group than it is like the first group of spring 

 herring. 



That this discrepancy actually occurs in Heincke's work may be 

 seen on reference to the following table :— 



* op. cit. Tab. u. Taf. p. 123. 

 t „ .. 149- 



% .. ., 156. 



From this it appears that the spring herring from Stralsund 

 resemble the autumn herring of the Gothland Bank much more than 

 they do another group of spring herring from the DoUart, and the 

 difference between the two groups of spring herring is nowhere 

 more marked than where the formulae are similar, that is, in the case 

 of the distance of the ventral fin. It would have been far better 

 to have employed, instead of an arbitrary formula, either the 

 averages themselves or to have effected a comparison by means 

 of curves based on these averages. 



Then it would be possible to form a true conception of the actual 

 relationship of the various groups of herring which Heincke investi- 

 gated, which is practically impossible under present conditions. 



Heincke's own investigations gave the following results : In the 

 case of spring herring, fifteen tables dealing with separate groups 

 yielded the correct average formula 2bII, i.e. 65 per cent, whereas 

 eight tables gave a different formula, i.e. 35 per cent. In the case 

 of autumn herring, seventeen tables gave the correct formula 2al 



