188 ON THE GROWTH OF 
that Grilse on their first arrival in rivers are small 
in size and long for their weight, some of them 
weighing only a pound and others less—I am at a 
loss to conjecture. 
Such are the principal experiments on the growth 
of the Salmon detailed in Mr. Young’s treatise; and 
the inference deduced from them is, that in its transi- 
tion from a Smolt to a Grilse, from a Grilse to the 
perfect state as to form and aspect, and also in the 
perfect state, the rate of growth is extraordinarily 
rapid during those portions of its existence which 
are passed in the sea, but that Salmon do not 
increase in weight while they remain in fresh 
water. 
Now, though it is an undoubted fact that great 
deterioration in the condition and, consequently, in 
the weight of Salmon uniformly takes place while 
they are engaged in perpetuating their species, yet 
that the prowth of young individuals which do not 
accompany their congeners to the sea is steadily 
progressive, observation and experiment plainly 
show. Salmon-fry from 7 to 8 inches long, having 
all the characters of the Parr, may be taken in 
the Conway and its tributary streams in small 
numbers late in the month of June, after the 
Smolts of the season have quitted those rivers; 
and occasionally I have obtained specimens of still 
larger dimensions, weighing four ounces. The 
physical cause, whatever it may be, which prevents 
