n had been vaguely surmised by many,
and it was generally admitted that the smaller fish were never found to
occur except in streams or tributaries to which the grown salmon had, in
some way, the power of access, yet all who have any acquaintance with
the works of naturalists, will acknowledge that the parr was universally
described as a distinct species. It is equally certain that all who have
written upon the subject of smolts or salmon-fry, maintained that these
grew rapidly in fresh water, and made their way to the sea in the course
of a few weeks after they were hatched.

Now, Mr Shaw's discovery in relation to these matters is in a manner
twofold; first--he ascertained by a lengthened series of rigorous and
frequently-repeated experimental observations, that parr are the early
state of salmon, being afterwards converted into smolts; secondly,--he
proved that such conversion does not, under ordinary circumstances take
place until the second spring ensuing that in which the hatching has
occurred, by which time the young are _two years old_. The fact is, that
during early spring there are three distinct broods of parr or young
salmon in our rivers.

1st, We have those which, recently excluded from the ova, are still
invisible to common eyes; or, at least, are inconspicuous or
unobservable. Being weak, in consequence of their recent emergence from
the egg, and of extremely small dimensions, they are unable to withstand
the rapid flow of water, and so betake themselves to the gentler eddies,
and frequently enter "into the small hollows produced in the shingle by
the hoofs of horses which have passed the fords." In these and similar
resting-places, our little natural philosophers, instinctively aware
that the current of a stream is less below than above, and along the
sides than in the centre, remain for several months during spring, and
the earlier portion of the summer, till they gain such an increase of
size and strength as enables them to spread themselves abroad over other
portions of the river, especially those shallow places where the bottom
is composed of fine gravel. But at this time their shy and
shingle-seeking habits in a great measure screen them from the
observance of the uninitiated.

2dly, We have likewise, during the spring season, parr which have just
completed their first year. As these have gained little or no accession
of size during the winter months, owing to the low temperature both of
the air