| OCR Text |
Show 50 ON IRREGULARITY IN THE GROWTH OF SALMON. [Jail. 13, of Professor Agassiz's* expressions (himself adverse to the transmutation theory) cannot be denied. In treating of the relations between animals and plants and the surrounding world, he says, " And yet, without a thorough knowledge of the habits of animals, it will never be possible to ascertain with any degree of precision the true limits of all those species which descriptive zoologists have of late admitted with so much confidence into their works. And, after all, what does it matter to science that thousands of species, more or less, should be described and entered into our systems if we know nothing about them !" . . . "Then we may learn with more precision how far the species described from isolated specimens are founded in nature, or how far they are only a particular stage of growth of other species ; then we shall know, what is yet too little noticed, how extensive the range of variation is among animals observed in their wild state, or rather, how much individuality there is in each and all living beings." No decided answer can be given to the questions at issue while so much of the commoner facts in the life-history of the Salmonidae are conjectural. Every scrap of information based on accurate observations is needed to unravel the phenomena, whether dependent ou reasons physiological or physical, teleological or pangenetical. EXPLANATION OF PLATE II. Illustrations of the variable growth of Salmonoids in tanks of fresh water. Fig. 1. Young of the Great-Lake Trout (Salmo lacustris?), being one among others reared from a batch of ova from Huningue, near Basle, and presented to the Society by Mr. Frank Buckland, 9th or 10th March, 1869. The specimen was nine months old, having been hatched about the middle of March; and the drawing was taken immediately after death, on the 15th December, 1869, natural size, i. e. 3-3 inches long. A few of the same brood were somewhat larger, others smaller. Fig. 2. A young Salmon (?) from Rhine ova, received as above. Length 1*95 inch; natural dimensions: sketched 14th December, 1869. Fig. 3. Another specimen of the same batch of Salmon (?), and corresponding to fig. 2 in age, viz. about 9 months. Natural size, -=2-7 inches, and, as in fig. I, figured immediately after death. The brackets, respectively lettered a, b, between the preceding figures, indicate the length (31 inches) of one of nine good-sized specimens of the same brood of Salmon (?), which died on the 6th October, or somewhere betwixt 6 and 7 months old. Had they lived until the middle of December, doubtless they would have grown as large as the Great- Lake Trout here represented. Fig. 4. Salmon (?) from Rhine ova, fully 2 years old, which, like the above, was reared and retained in the Society's freshwater aquarium at the Regent's Park. Hatched February 1866, died 14th April, 1868. The figure, natural size and colour, taken immediately after death, shows the assumption of the silvery Smolt-coat, indicative of the migr* at oArny Eimspsualys eo.n Classification (London, 1859), pp. 85, 86. |
