| OCR Text |
Show 28 MR. F. DAY ON RACES AND [Jan. 15, individuals of whatever size, but, as far as our experience reaches, is even often characteristic of the species of a genus"1. Likewise, in his 'Introduction to the Study of Fishes,' 1880, p. 159, he observes, " The ova of Teleosteous Fishes are extremely variable in size, quite independently of the size of the parent species. The ova of large and small individuals of the same species, of course, do not differ in size." This brings us to the consideration of whether it is possible that increased size of eggs may lead to augmented size of offspring, irrespective of the question of changing the locality they inhabit, or increasing the space or amount of water in which they reside. The following interesting experiment was instituted fourteen months since by Sir James Maitland. Two batches of Lochleven Trout were spawned in the winter of 1882 on November 2nd, the parents of one having been hatched in 1875, and of the other in 1876. The eggs were similarly treated, and hatched in January and February 1883. In the garden in front of Sir J. Maitland's house at Craigend two ponds have been constructed for the reception of young fish, each of the same width and 100 feet long; one is nearly on a level with the other, and the same stream runs through each. Into these ponds the two lots of fry were turned-those from the older or 1875, or seven years' old parents, having the lower pond ; those from the younger or 1876, or six years' old parents, having the upper pond, while they were fed and treated in an identical manner. On November 29th we examined these two ponds, the fry in the upper of which, or from the younger parents, seemed to average about 2\ inches in length, while those in the lower pond appeared to average about 3 | inches in length; showing that from the eggs of the older parents had emanated the more satisfactory offspring. W e next proceeded to draw a net through each pond; and I selected three young fish from the upper and five from the lower series as among the finest examples of each batch. These fish gave the following results *.- Upper pond, from 1876 parents. Length. Bars. Bars. inches. 3*5 13 13 30 13 12 2*9 14 13 Average. ... 3*1 13^ 12| These fish were more spotted than those in the lower pond and had more red marks. The dorsal fin had a white front edge, as in young Brook-Trout 1 Genus Brachymystax, Giinther. " Even if Salmo flaviatilis should prove to be the male of Salmo coregonoides (the type of the new genus), still the small size of the ova would be a character of sufficient importance to separate these fishes generically from Salmo," Oatal. Fish. Brit. Mus. vi. p. 163. |
