the Salmon, Herring, and Vendace. 477 



than had they continued in the bed of the river ; and, after having 

 cast the slough, will live about ten days (seldom or ever longer) 

 in water unchanged, apparently thriving, growing and darkening 

 in colour (if exposed to the light) every day. But they have not 

 been observed to eat any thing offered them, and they invariably 

 die, whether the water be changed or not, after attaining the 

 length of about an inch and a quarter. That they live and 

 thrive thus in unchanged water, must be the effect of habit. We 

 shall presently find that the grown smolt cannot do so, and that 

 when confined it quickly sickens and dies, a fact of the most 

 unexpected and extraordinary kind, and perfectly unknown to me, 

 previous to these experiments and observations. I request it 

 here to be understood, that all these remarks are made from per- 

 sonal observation, and are in no shape founded upon hearsay 

 evidence, even of the most respectable kind. 



I have already remarked, that, on the 25th March, the spawn- 

 ing bed was again reopened before us : nearly all the young fish 

 had cast the outer shell. Now, it is almost certain that this took 

 place two days before, or on the 23d March. Thus we have 1 42 

 days from the deposition of these ova in the gravel-bed by the 

 spawning salmon, or exactly twenty weeks; and though this 

 period may vary a week or two, it will require much stronger 

 evidence than has as yet been submitted to the public, to induce 

 me to believe that these variations ever amount to any thing very 

 considerable. Ova deposited, as has been said, upon the 1st 

 April, would require to be developed before the 1st June, since 

 no one has ever ventured to affirm that smolts are taken, or 

 were ever seen in rivers after that time. Hypotheses of this kind 

 require that the ova of the salmon pass through, in eight weeks, 

 those changes which, under the usual circumstances, require 

 twenty for their perfection ; and though this is just possible, it is 

 any thing but proved. Wheat sown in October and in March 

 will ripen about the same time ; but when I am told that salmon 



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