THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
[SECOND SERIES.] 
No. 28. APRIL 1850. 
XXII.—WNotes on the Salmon and Bull-trout. 
By Joun Brackwatt, F.L.S 
In a short paper on the Salmon, Salmo salar, Fi tahed in the 
‘Annals and Magazine of Natural History,’ vol. xi. p- 409, I 
have endeavoured, on physiological principles, to establish the 
fact, that the erowth of that valuable fish is not by any means so 
rapid as it is commonly supposed to be by ichthyologists. Ob- 
servations having relation to this subject and also to the ceconomy 
of the bull-trout, Salmo eriox, have been continued to be made, 
as suitable occasions presented themselves, up to the present 
period, on a plan similar to that previously adopted, and I am 
induced to insist upon the decided advantage which a recourse 
to physiological phenomena possesses in investigations of this 
kind over the customary practice of mechanically marking fish 
as objects of experiment, im consequence of the various sources 
of error to which the latter mode of proceeding is exposed. 
Persons, in their endeavours to determine the rate of growth 
in fish by marking specimens, too frequently employ subordinate 
agents to carry their intentions into effect, to whom not only 
their system of marks is of necessity made known, but the anti- 
cipated result is also communicated. Now should it so happen 
that the agents are dependent upon their employers, or in any 
respect interested i in making the event appear to coincide with 
their preconceived opinions, the desired object may be easily 
attained either by secretly marking specimens of a larger size 
than those which they were instructed and perhaps observed to 
select for the purpose, and by exhibiting them alone when re- 
captured, or by adapting the marks to fish subsequently taken, 
whose dimensions appear to be best suited to promote the end 
they have in view. Besides, it often happens that all the par- 
ticulars of the undertaking transpire, and becoming widely cir- 
culated, other parties resident in the neighbourhood may apply 
similar marks to fish of different sizes captured in the. same 
Ann. & Mag. N. Hist. Ser. 2. Vol. v. 16 
