370 MR SHAW ON THE GROWTH AND MIGRATIONS 



summer months, when the real species to which they belonged was less difficult 

 to determine. I then placed them in ponds, with a good supply of wholesome 

 water, and spawned them artificially when the due season arrived. This method, 

 however, I never considered as a very legitimate mode of procedure, from the cir- 

 cumstance of a possibility of error from an improper selection and combination of 

 the parent fishes, and I therefore watched every opportunity of capturing them 

 in the act of depositing their spawn in the natural bed of the streams or tribu- 

 taries, each fish accompanied by a mate of its own selection. It was not, how- 

 ever, until the autumn of 1839 that I had the good fortune to capture the parent 

 fishes under these circumstances, and this I effected by the aid of my fowling- 

 piece. 



On the 1st of November 1839, having discovered a pan* of sea-trouts (See 

 parent specimens A) engaged in depositing their spawn in the gravel of one of the 

 small tributaries of the river Nith, and being unprovided at the moment with the 

 necessary apparatus for their capture, I had recourse to shooting, as the only mode 

 within my power of insuring instant possession of them. However, the vigilance 

 exercised by both parents in protecting the ova from being devoured by multi- 

 tudes of smaller fishes which surrounded them, rendered it exceedingly difficult 

 to seize the precise moment at which both might be disabled by one discharge of 

 the piece. This, however, was at length effected by shooting immediately across 

 the heads of the pair as they lay parallel to each other, but more by the influence 

 of concussion, than the actual effects of the shot, they being at the time in about 

 six inches depth of water. Having taken them ashore, I proceeded to spawn 

 them by pressing the ova from the body of the female into a little water by the 

 side of the stream, and afterwards, by the same process, I caused the milt from the 

 body of the male to mingle with it. I then removed the impregnated ova in a 

 copper-wire gauze bag, in which some fine gravel had been placed, to a little stream 

 connected with my experimental ponds. The temperature of the water was at 

 this time 47, but during the winter it ranged a few degrees lower. By the 40th 

 day after impregnation, the embryo fish were visible to the naked eye, and on the 

 14th January 1840 (75 days after impregnation) the fish were excluded from the 



egg- 



The specimen No. 1 exhibits the young as it existed the day on which it was 



hatched, with a single specimen of the ovum to shew the condition the day before 

 hatching. The brood at this, the earliest period, exhibit no perceptible difference 

 from the young of the salmon of a corresponding age, except that they are some- 

 what smaller in size, and of a paler blue upon the body, the vitelline bag being 

 likewise of a lighter red. 



The specimen No. 2 is the young sea-trout of two months old, taken from 

 the ponds on 17th March 1840. It is about 1 inch in length, and has assumed 

 those lateral markings which seem to characterize the earlier stages of all the 



