19 
in every fish. They are not to be seen 'externally, but when the fish is 
gutted, it is easy to find the worms; and these cod are such a bad article 
of commerce that "you can never sell that sort more than once at the 
same place” — then people know about it. 
When I arrived at these parts this year (20th Octbr.), 13 cod from a 
fishing-boat were examined, and they were nearly all, particularly near the 
anus, but also in the parietes of the abdominal cavity, to such a degree 
infested with worms that they could not possibly be used for food without 
loathing. I have formerly shown that the herrings in the neighbourhood of 
Gøteborg are also more infested with worms (Åscaris elupearum) than those at 
other places, c. 25 p. c. of the full-grown herrings having got them, while 
I found only ec. 17 p. e. at Lolland, and none at all at Bornholm. Now, 
certainly, we do not know at all how quickly the stock of fish in a sea can 
be infested with these parasites, but when they have got them, they certainly 
keep them for some length of time. These cod must therefore remain in 
nearly the same places for rather a long time, and I should think that just 
these infested cod are those which immigrate into our seas when small, 
and stay there till they are 2 years old. There will then be time enough 
for the worms, which must be particularly fond of the said waters, to be 
developed and to "infect” the whole stock. The cod I examined were all 
about 2 years old. There is nothing here to prevent these cod from emi- 
grating to the North Sea afterwards and become "large cod”; for in these 
the said worms are not rare, even though not all of them are infested as 
in the said waters. 
Of the age-groups of the cod, and of its growth in general, I have said 
something above. We are acquainted with its growth in the two first years, 
in which it reaches an average size of c. 14—15 inches (35—40 ctm.) (see 
above p. 5, table I), and becomes, in part, mature; but the higher ages we 
do not know very exactly. K. E. Earll (U. $. F. C. Report for 1878, Part 
VI, 1880) mentions 4 groups of cod between 0 and 22 inches, but he has 
given no proof of them. Nor has G. 0. Sars given any proof, by measuring 
the fish, of the correctness of his estimate as to the growth of the cod; and 
it js my opinion that he is wrong in his estimate; they do not grow so 
quickly as he supposes. 
H. Krøyer, who has seen so many cod in the Lofoten, states one of 
the very largest to be 54 inches long; but that must have been a veritable 
giant. The common Lofoten cod ("Skrei”) are generally but 30—40 inches 
long, and so large are also the full-grown North Sea cod. Many cod of 
the same size are also fished in our waters in the winter. Yet they are not 
by far so frequent here as those whose measures are stated in table I. In 
table I we reach only 25 inches; we have, consequently, not at all to do 
with full grown cod, properly so called, for these I suppose, as I have said, 
to be between 30 and 40 inches. How the cod between 30 and 20 inches 
(see table I) åre grouped, I do not know; probably there is here an age- 
