78 PHYSOSTOML 



parr," is the younger individual of the same species only entering upon its second 

 year. On instituting a careful examination on May 15th, 1834, of a river where 

 salmon had spawned the preceding winter, Mr. Shaw found a vast number of 

 very small but active fish above an inch in length, some of which were placed in 

 two ponds. In May, 1835, these fish were on an average 3| incbes in length and 

 corresponded in every respect with the parr of the same age which occurred in 

 the river, in May, 1836, they were transmuted into smolts and measured 6^ inches 

 in length. 



A number of parr were placed in the Brighton Aquarium in a fresh water 

 tank, and when the month of May came round some had assumed the livery or 

 protecting silvery scales of the migratory smolt. Sea water was now gradually 

 introduced and all became smolts, thus showing that saline water is not necessai'ily 

 fatal to parr as generally supposed, at least at the time they are on the verge of 

 attaining their smolt condition. 



Mr. Ashworth, in certain experiments which were instituted at Stormontfield, 

 near Perth, showed that a portion of the parr assumed the smolt dress and 

 descended to the sea shortly after the close of the first year of their existence, 

 returning again as grilse weighing from 5 to 9~ lb. within 20 months subsequent 

 to the deposition of the ova, while some of the same lot remained behind as pai'rs, 

 weighing an ounce at the period of the return of their brothers and sisters above 

 referred to. It has also been remarked that whether a river is an early or late 

 one the descent of the smolt generally occurs during the spring, between March 

 and June. Mr. Dunbar who annually hatches about 500,000 in the Thurso river, 

 in the county of Caithness, informed Mr. Young that about eight per cent, became 

 smolts at the end of the first year, and about 60 per cent, at the end of the second 

 year, and the remainder or 32 per cent, at the end of the third year. 



Having thus far traced the salmon egg to the pink or parr, and on to the 

 stage of migratory smolt, which congregates in shoals, it becomes necessary to 

 follow this latter fish until it has migrated to the sea, from which it never 

 returns, similar to the fish which descended there, but instead a larger form, 

 weighing more pounds than it did ounces, a miniature salmon in short, and termed 

 grilse, ascends in shoals. The scales of the silvery smolt come off very readily on 

 the fish being handled, and underneath may be seen transverse bars, the livery of 

 the parr. 



Mr. W. Brown (Stormontfield Experiments, 1862, p. 7) observed upon 

 having in February, 1836, caught a dozen and a half of parr in the Tay, he kept 

 them confined in a stream of running water, and by the month of May the whole 

 of them had become smolts ; but some had leaped out of their confinement in 

 their struggle to find their way to the sea, and were found dead upon the side of 

 the pond. Mr. Upton, in the autumn of 1835 and the following spring, according 

 to Yarrell, transferred some " pinks," none of which exceeded 3^ inches in 

 length, from the Lune to a lake termed Lillymere, and which has neither outlet 

 from other waters by which fish can obtain access, or any obtain exit, and no 

 communication with the sea. In August, 1837, two salmon peal, measuring 

 14 inches in length and weighing 14 ounces, were taken with a fly, in excellent 

 condition in every way, and in July, 1838, another small salmon was caught equal 

 to the first in condition and colour, about 2 inches longer and 3 ounces heavier. 

 A " pink " was transferred to a well at Whitewell in November, 1837, and removed 

 thence as a smolt 6j inches long in July, 1838. These and other similar instances 

 would appear to point out that, as in the trout so in the salmon, the larger the 

 extent of the water in which the fish resides, so much the more probable is it that 

 it will rapidly attain a larger size. 



From the foregoing it appears that it is the natural course for smolt to migrate 

 to the sea, but that a compulsory detention in fresh water is not necessarily fatal, 

 a subject to which I shall refer further on (see p. 80). When at Montrose at the 

 end of June this year, several smolts were taken from the stomach of a saithe, 

 Gadus virens, captured in the sea a couple of miles from the coast. A similar 

 occnrrence was noticed at the same place in December last year, the fish which 

 had eaten the smolt being a whiting. When at Aberdeen in July, 1882. Mr. Sim 



