WHICH HAVE NEVER DESCENDED TO THE SEA. 455 



At the same establishment a suggestion which had been advanced— that the anomaly 

 rf some parrs migrating at the end of one year after hatching, and the remainder 

 tfter two seasons, must have been caused by the first being the produce of Salmon, 

 vnd the second of grilse-was clearly refuted. The fry, which numbered about 200 000, 

 *rere solely the produce of 19 male and 31 female Salmon, spawned in 1859 ; and ot these 

 some remained in the ponds as parr, while others migrated seawards as silvery smo Its. 

 These same experiments showed that marked grilse of one year return as Salmon the 

 next • that all the smolts of one year do not return the same year as grilse, the one hall 

 returning next spring and summer as small Salmon (I. c. pp. 92, 93) ; also that marked 

 smolts w°ere caught as grilse the first season and Salmon the second (I. c. p. 94). 



Asain, some authors have held that were Salmon able to migrate into large freshwater 

 lakes, where a sufficiency of suitable food existed, they would be able to return to the 

 streams where they had been reared as well-developed Salmon, a theory denied by 

 others, who assert that Salmon never increase in weight in fresh water ; but it this were 

 so, how do they grow at Howietoun ? # 



Dr Murie (Proc. Zool. Soc. 1868, p. 219) gave an account of some Rhme Salmon 

 (Salmo salar), hatched in the Gardens of the Zoological Society, in February 1863 and 

 which lived in fresh water up to 1868. In May 1805, at the usual period of migration, 

 those which were smolts tried to leap out of the tank; similar phenomena occurred m 

 1866 and "it was further observed that those which had assumed the silvery dress in 

 the beginning of the year, again lost it in the autumn and became distinctly parr- 

 marked " In this autumn a good many died, some in the smolt, others m he parr- 

 livery ; and 1867 was a repetition of 1866. During the first and second years t he _ young 

 fish seemed to grow, and attained a length of from 3 to 6 inches During he third and 

 fourth year they grew much slower, and attained to from 5 to 7 inches m length ; onl> 

 I lived to the'fifth year. These fish were kept in a small tank with a running 

 stream of fresh water, a fact which is very necessary to bear m mmd, because, although 

 the conclusion drawn that the fishes retained in fresh water were subject to an arrest ot 

 growth, such may have been due to the small space in which they were confined, or 

 the limited amount of water which they obtained, irrespective of which, the changes ot 

 temperature may have been great. 



Yarrell ('Growth of Salmon in Fresh Water ') remarks that the view that the rate ot 

 growth in young Salmon has some reference to the size of the place to which they are 

 restricted, receives further confirmation in these river, lake, and well specimens. The 

 molt taken from the well in July 1838, where it had been confined ^^™ 

 rather smaller in size at that time than the smolts in the preceding April, though both 

 were Pinks of the same year, namely 1837 . The smolt taken from the lake in August ^1838 

 which then measured 7* inches, had also grown more rapidly than that in the weU but £ad 

 not acquired the size it would have gained had it been allowed to go to sea Further ,t 

 Lay be observed, that the Salmon peal from the lake in August 1837, then 8 mon hs o d, 

 Thou h perfect in colour, is small for its age ; while that of July 1838 or 29 months old 

 L comparatively still more deficient in growth, supposing both fish to have resulted 

 Lm Xks of the year 1836, and been put into the lake at the same time ; ot which there 



SECOND SERIES.— ZOOLOGY, VOL. II. 



