100 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
though they may not always be eaten. The reproductive 
organs are very large in full herrings and may attain a weight 
of about 1/7th of the total body weight. As the season 
advances this proportional weight of ovaries and testes rises, as 
is shown in the following Table, where Hjort’s scale of stages 
of development is adopted. 
Stages I to II are virgin fish with very small ovaries and 
testes ; 
Stages III to V are fish with large ovaries and testes, not 
quite“ full” herrings, but approaching this condition ; 
Stages VI to VII are “ full” fish which may even be 
actually spawning. 
‘“ Spent” fish are here included in Stage I. 
Manz Summer Herrings, Stages of Development. 
J-II. ITI-IV-V. VI-VII. 
May ... ae oie coal’ 72 ss 
June ... alk use ae 88 a 
ediuhiys te. Ba eae bs 49 72 at 
August oe ee o 5) 46 20 
Sent. oua wink = se 3 ia ele . 94 
Altogether 475 Manx fish were examined individually 
during the two seasons of 1916-17. It will be seen from the 
above results (which can be made more detailed, if necessary, 
by reference to Riddell’s report on the 1913 fishery)* that the 
size of the roes and milts gradually increases as the season goes 
on. With this increase in the bulk of the gonads, the nutritive 
value of the herrings increases. Towards the end of the season - 
the fish spawn, the roes and milts shrink up and decrease to a_ 
very small] fraction of the total body weight, and the nutritive 
value falls off very greatly. 
But accompanying this increase in the mass of ihe pee | 
ductive organs there is also an increase in the weight of the fish 
* Ann. Rept. Lancashire Sea-Fish. Laby. for 1914, pp. 109-138. - 1915. 
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