r,(jO MR SHAW'S EXPERIMENTAL OBSERVATIONS ON THE 



second -winter in the river, during which period the males shed then- milt, and are 

 foimd continuing their land along'with the female adult salmon, although stiU bear- 

 ing all the external markings of the parr, as I shall afterwards more particularly 

 mention. No. 8 is a specimen eighteen months old, taken from pond No. 1, on 

 the 14th November 1838. It measures inches in length, and has now attained 

 that stage when all the external characteristic markings of the parr are striking- 

 ly developed, and, in point of health and condition, cannot be exceeded by any 

 taken ft-om the river. AU the males, at the age of eighteen months, of the seve- 

 ral broods in my possession, last autumn (1838) attained a most unportant coiTO- 

 borative stage, viz. that of shelving a breeding state, by having matured the milt, 

 which could be made to flow freely from their bodies, by the slightest pressure of 

 the hand. The females of the same broods, however, although in equal health 

 and condition, did not exhibit a corresponding appearance in regard to the matu- 

 ring of roe. The male and female parrs in the river, of a similai- age, are found 

 respectively in precisely a corresponding state, which may surely be admitted as 

 most important evidence in support of the fact, that all these individuals are, 

 in truth, specifically the same. 



No. 9 is a specimen two years old, taken from pond No. 1, on the 20th May 

 1 839, after having assumed the migratory dress. The commencement of the change, 

 which was perfected by the whole of the broods about the same time,* was first 

 observable about the middle of the previous April, by the caudal, pectoral, and 

 dorsal fins assuming a dusky margin, while, at the same time, the whole of the 

 fish exhibited sjmptoms of a silvery exterior, as weU as an increased elegance of 

 form. The specimen in question, so recently a parr, exhibits a very perfect 

 example of the salmon fry or smolt. 



When the migratory change takes place in the young salmon in the ponds, 

 a marked alteration also occurs in their habits. While in the parr state, they shew- 

 no disposition to congregate, but each individual occupies a particular station in 

 the ponds, and should any one cjuit his place with the view of occupjing the po- 

 sition already possessed by another, the intruder is at once expelled with an a])- 

 parent degree of violence. But so soon as the whole bi"ood has perfected the mi- 

 gratory dress, thej' immediately congi-egate into a shoal, and exhibit an anxious 



are considered to be the fry of that year ; at this time smolts of six inches and a half are also taken." — 

 See Yarrell's Supplement to British Fishes, page 6. 'The fry of the same year, in mild winters, are only 

 quitting the gravel in April, at which stage they measure not more than one inch — J. S. 



• One or two of each of the three broods assumed the migratory or smolt dress at the age of twelve 

 months. This circumstance I am disposed to attribute to the high temperature of the spring-water 

 ponds, which I have no doubt has hastened the change. I am greatly strengthened in this opinion by the 

 fact of no instance of a similar change having occurred with individuals reared in similar ponds supplied 

 with water from a rivulet, the temperature of which throughout the year ranges pretty nearly with that 

 of the River Nith. 



