372 MR SHAW ON THE GROWTH AND MIGRATIONS 



pose fin is dark brown, margined with red ; the caudal rays are of a light colour 

 near the base, running into dark orange, terminated by a faintly marked double 

 margin of black. The spots on the back and sides vary much in individuals of 

 the same brood, but the specimens produced exhibit a pretty correct example of 

 the general markings of the brood. The spots prevail principally along the back, 

 with a few below the lateral line. Each spot is surrounded by a circle of a lighter 

 colour than the general surface of the body, and this appears to be a prevailing 

 character of the trout species, and one which the sea-trout fry exhibits even after 

 having assumed the migratory dress, when every other feature of resemblance to 

 the common trout has disappeared. The spots on the gill-covers are also more 

 numerous than those of the salmon, generally amounting to 5 or 6. 



From the ovum up to the migratory state, the natural economy of the sea- 

 trout appears to bear a resemblance to that of the real salmon. However, from 

 the latter stage to that of the herling (which, as I have said, is beyond all doubt 

 the young of the sea-trout), there is certainly a singular departure from the uni- 

 form progress of that species. It appears from experiments very carefully con- 

 ducted, that there is always a certain number of individuals of both sexes (pro- 

 bably about one-fourth of each brood) that never assume the silvery exterior, or 

 migratory dress; and even if those which have assumed that appearance be detained 

 in fresh water for a month or two, they will reassume the dusky coating ; and 

 by the beginning of the ensuing autumn, the females mature the roe sufficiently 

 to reproduce their species with young males of corresponding age. As an evi- 

 dence of this fact, I may here detail the particulars of an experiment made upon 

 individuals in the condition alluded to. Having discovered, on the 25th of No- 

 vember last, that the whole of the females of the brood, as well those which had 

 been silvery as those which had not, were exhibiting signs of being in the breeding 

 state, I took six individuals (three males and three females, the latter having 

 matured their roe for the first time at the age of 2^ years, the former being 

 milters for the second time), and commingling the milt and roe, I placed the im- 

 pregnated ova in wire bags in a stream connected with the ponds, and in 76 days 

 thereafter they were hatched, and the brood now exhibits as healthy a condition 

 in every respect as those produced by adult parents from the sea. 



From these facts, it may perhaps be inferred that the sea-trout bears, in some 

 respects, a closer affinity to the common trout than it does to the real salmon ; 

 and that that portion of each brood which does not assume the migratory dress, 

 but matures healthy roe and milt, and is capable of reproduction at the proper 

 season without going to sea, forms one of the supposed varieties observable in all 

 rivers to which migratory trout have access. It is then by no means improbable, 

 that portions of each brood are permanent residents in fresh water, as they are 

 never observed to migrate in a dusky state, along with the shoals of silvery fry, 



