494 
Various food fishes common to the coast of 
Norway, such as Gadus virens, G. callarias, 
G. eglefinus, Lycodes esmarcku, Molva vul- 
garis, M. byrkelange, Brosmius brosme, Hippo- 
glossus vulgaris, Pleuronectes platessa, P. 
limanda, Sebastes marimus and others have 
round worms on the liver; but only those that 
commonly live near the coast or in shallow 
water, such as G. callarias and G. virens seem 
to be considerably affected. 
When many round worms find their way 
into the muscles of the body of the fishes its 
health is impaired. The nematode lodges 
itself between the metameres of the muscles 
where it becomes encysted. The effect on the 
fish is marked. Those with a considerable 
number of intermetamerically encysted worms 
become sluggish in movements and in time 
are not able to chase their food. Consequently 
these fish become an easy prey to their enemy. 
Examination of several specimens of G. virens 
and G. callarias, from various localities, 
showed that the muscles of apparently healthy 
specimens were also infected. Fortunately the 
larger fish on the coast of Norway have not, 
as a rule, many enemies among themselves; 
but if the nematode invasion becomes too 
great they may succumb from lack of ability 
to catch their own food. This is particularly 
true of carnivorous species. On the other 
hand, smaller specimens, if infected, are easily 
preyed upon. ‘The cause for this disease must 
be sought in the diet of the fish. 
Seventeen years ago, when the writer was a 
resident of northern Norway, this disease 
among food fishes was unknown to the con- 
sumer of fish. Kveisa were always known to 
be on the liver, for they could be readily seen; 
but they were not considered to be of any 
consequence. Jf the liver was prepared for 
table use, which is commonly done when it is 
obtained absolutely fresh, its capsule and trabe- 
cules were removed together with the kveisa. 
But if the consumer at dinner time finds kveisa 
in a morsal of fish he naturally loses his ap- 
petite at once. This in consequence interferes 
with the use of such kinds of fish as a diet. 
In fact, newly caught codfish which formerly 
were one of the most tempting offers to any 
SCIENCE 
[N. S. Von, XLVIII. No. 1246 
family table, had little chance in 1917 at the 
villages of Rorvik i Namdalen, Brénnéy, 
Sandnessjoen and Stokmarkness. The people 
knew that the fish were diseased and did not 
eare to buy them. ; 
The fishing industry has been one of the 
largest industries in Norway for many years. 
The intestines have not been utilized except 
by farmers, in northern Norway, who use 
them as fertilizer. Those people, however, 
who depend entirely on fishing for their living 
throw the intestines overboard when the fish 
is sloughed. It is probable that healthy fish 
by feeding on infected viscera acquire so many 
of the parasites that they succumb to their 
injurious effects. 
Along the coast of Norway, the younger 
generations of shore cods (Gadus callarias) 
and bluefish (Gadus virens) commonly seek 
shallow water for feeding purposes. At fish- 
ing villages where a great deal of cleaning of 
catches takes place the young fish find ample 
food from discarded intestines, and as all 
the viscera are as much inffected-as is the 
liver, it may be fair to assume that this mate- 
rial is the cause of the nematode infection. 
It is conjectured that when food gets scarce 
and the vitality of the fish decreases the effect 
of the nematode inroad is increased. This 
was indicated by the fact that all of the poorer 
specimens, of the species G. callarias and G. 
virens, which were examined, were much more 
infected with nematodes than were the health- 
ier ones. 
It may be fair to assume that the attack of 
nematodes on marketable fishes in Norway 
may become an economic problem of con- 
siderable importance. If, however, it is proved 
that the worms found in the flesh are of the 
same species as those commonly found on the 
viscera, the present extensive infection may be 
remedied by stopping the feeding of young 
fish on infected viscera. The danger of this 
infection does not lie in transferring the 
nematode parasite to man, for that is im- 
probable, but it is unpleasant to eat worms. 
The problem is, to what extent will the dis- 
ease diminish the use of nematode infected 
fish as a diet; and decrease the number of the 
