170 
SAl.MON. 
regular ai-rangeinent of this army as is described by the 
Prussian naturalist, since, if it at all exists, it mus e la e 
to be broken up by the multitude of enemies and dangers u 
which these fish are exposed, and of which man and his 
engines are not the least formidable. But after they h 
enLed the river it is uncertain how long tliey keep together 
since through the summer they are found single or in small 
parties, and accessions are made in continued arrivals, until, as 
Sie autumn advances, the newly-arrived fish present a diffeien 
aspect, and are urged on towards a different ohject._ It has 
been contended that of all the fish which come into fresh 
water from the early months of the year none return to the 
sea until they have shed their spawn, which function for the 
most part is only performed in the winter, or from about the 
month of November to January, although in some instances, 
and in particular districts, it may he so earlj^ as the latter 
part of September, or as late as in March. But theie does 
not appear any proof of this long continuance of the indivMual 
adult Salmon ‘in rivers, and the contrary seems more highly 
probable. Thus it is admitted that in a short time after it 
has entered the river an unfavourable change as regards i s 
plumpness and delicacy as food is perceptible; and so speedily 
is this produced that some observers profess to ^^le to 
detect it in a few hours, and it is allowed to be visible after 
a few weeks, by which time also the parasitic animal which 
in the sea had fastened itself to the skin has fallen from its 
holdfast. But if so hurtful a change has taken place as can 
be discerned in this short space of time, we can scarcely 
suppose that the same fish will remain in such a healthy state 
for many succeeding months as is necessary to a successful 
effort of spawning, being also during that time exposed to a 
succession of the same depressing influences. Me add, that 
there appears no means by which we can feel assured that a fish 
which is known to he in perpetual movement has not retraced 
its course to the sea, to be replaced by a new arrival, which 
circumstance is the more probable as it is known that the 
fixed nets employed at the entrance of rivers do just as fre- 
Quentlv intercept those which may be coming down as those 
which are only moving up and down with the tide. It seems 
certain, also, from repeated observation, that after its arrival 
