Fishes. 3759 



is every reason to believe that those which were placed about 3 inches 

 in the gravel have all been hatched. A live fish brought from the 

 spawning-bed leaped out of the vessel in which it was kept and spee- 

 dily died, and the two mentioned in the published letter also died in 

 the course of about ten days, probably in consequence of the disturb- 

 ance to which they were exposed from the curiosity of those who came 

 to see them, and who were desirous of observing the extreme velocity 

 with which they moved round the vessel, even while the vitelline bag 

 was still attached to the abdomen. The spawning-bed was formed in 

 a small run of spring water, which is never affected by the frost ; it 

 was cleared of minnows, young trout, &c, and at each end of a space 

 of about 20 yards, whins were placed of a good height, kept down 

 with stones, to prevent the entrance into it of other fish. After some 

 observations respecting minnows, Mr. Fisher adds : — " We have 

 proved the fact that the river Swale may be again stocked with sal- 

 mon, provided we can make arrangements with the proprietor of a 

 mill-wear, twenty-five miles from this place, to let the fish, on coming 

 up from the sea, have ' free gap ' from time to time." 



On these letters Mr. Hogg observes that it seems to him there can 

 be little (if any) doubt that, with the precautions indicated, a vast in- 

 crease of salmon might be obtained, and a sure and valuable source 

 of wealth be secured in many suitable streams in which no salmon are 

 at present found ; and the same artificial process of breeding might 

 likewise be applied to trout with an equally advantageous result. He 

 suggests that the breeding might also be carried on in large wooden 

 boxes or cases, having a layer of gravel at the bottom 4 or 5 inches 

 deep, in which the ova and milt, or impregnated ova, might be buried, 

 and the cases filled with pure water, which might be kept constantly 

 fresh by allowing a small stream to run into them. When the fry had 

 grown sufficiently strong, they might be conveyed to any distance in 

 tubs filled water (which might be occasionally renewed), and having 

 their tops perforated with holes. On the subject of the distribution 

 of the species of fresh-water fishes, Mr. Hogg refers to the presence 

 of trout and other fishes in mountain streams and alpine lakes, for 

 which it seems difficult to account ; but he suggests that as the pre- 

 sence of unusual plants in similar circumstances is only to be ac- 

 counted for by the seeds having been dropped by birds, the problem 

 with regard to fishes might be naturally solved in an analogous man- 

 ner, their fry having been conveyed to these distant localities by 

 means of water-birds. 



