548 MR SHAW'S EXPERIMENTAL OBSERVATIONS ON THE 



wholesome water. There they continued to thrive remarkably well, and were 

 seen catching flies and other insects, and sporting on the surface in perfect health. 

 In the month of April following (3 834), they began to assume a different aspect 

 from that which they exhibited when first put into the pond, and this change was 

 evident enough even while they continued swimming at large in the water ; but 

 wishing to examine them more particularly, and at the same time to convince 

 others of the fact of their having changed their external character, I caught them 

 with a casting-net, on the 17th May 1834, and satisfied every individual present 

 that they had assumed the usual appearance of what are called salmon smolts or 

 fry. They were now of a fine deep blue upon the back, with a delicate silvery 

 appearance on the sides, and the abdomen white ; these silvery scales came easily 

 off upon the hand. A circumstance occurred about the fii-st week of May, which 

 it may be proper to mention, as illustrating in some manner what may be deemed 

 the migratory instinct of these fishes. They setoied to me at this time to be de- 

 creasing in nmnbers, and I found, on examination, that some had leapt altogether 

 out of the pond, and were lying dead at a short distance from its edge. 



In March 1835, 1 again took twelve parrs from the river of a larger size, that 

 is, about six inches long ; they then bore the perpendicular bars, and other usual 

 characters of that fish. These I also transferred to a pond prepared for the pur- 

 pose, and, by the end of April, they too assumed the characters of the salmon-fry, 

 — the bars becoming overlayed by the new silvery scales, which parrs of two years 

 old invariably assume before departing towards the sea. From these experiments 

 I had no doubt that the larger parrs observable in rivers in autumn, winter, and 

 early spring, were in reality the actual salmon-fry advancing to the conclusion of 

 thew second year, and that the smaller summer parrs (called in Dumfriesshu*e 

 May parrs), were the same species, but younger as individuals, and only entering 

 upon their second year. This, then, I conceived to be the detection of the main 

 error of preceding observers, who had uniformly alleged that salmon-fry attain a 

 size of six or eight inches in as many weeks, and after the lapse of this brief pe- 

 riod take their departure to the sea. It is the rapidity with which the two year 

 old parr assumes the aspect of the salmon-fry that has led to this false conclusion, 

 and superficial or hasty observers, taking cognizance, 1st, of the hatching of the 

 ova in early spring, and, 2dly, of the sea-ward migration of smolts soon after- 

 wards, have imagined these two facts to take place in immediate or speedy suc- 

 cession. I may now mention what actually becomes of these young fishes for 

 some weeks after they are hatched. 



That the fish in question should not be found in the river in an earlier state 

 than that in which it is named the May or summer parr, had long appeared to 

 me to be an extraordinary and perplexing circumstance. I therefore made a mi- 

 nute examination of the streams where the old salmon had spawned the preced- 

 ing winter, and I there found in vast numbers a very small but active fish, which 



