Page:The Zoologist, 4th series, vol 2 (1898).djvu/316

284 conditions.4. That each bird has to separately acquire its experience, and well remembers what it has learned." And that, therefore, on the whole, the theories of Bates and Wallace are supported by the facts detailed.

following extracts are from an excellent summary in the 'Globe':—

"In his introduction to a Report just issued by the Scotch Fishery Board relating to investigations on the life-history of Salmon, Dr. D. Noel Paton (Superintendent of the Laboratory) states that the curious life-history of the Salmon has always been a subject of the deepest interest, not only to the zoologist and physiologist, but also to the sportsman and the fisherman. In spite of the most careful study by scientific investigators, the migrations of the Salmon, and the various changes in condition which it undergoes, are even now far from being fully understood, and the careless observations and foolish traditions of keepers, fishermen, and ghillies have only served to involve the matter in a deeper cloud of mystery.

"Questions to be answered.—What force urges the fish to leave its rich feeding-ground in the sea? Is it necessary that it should enter fresh water in order to perform the act of reproduction? Does it require or procure any food during its sojourn in the river, and, if not, how is it able to maintain life, and to construct its rapidly-growing genital organs? In the female the growth of these is enormous. In April or May the ovaries constitute only about 1.2 per cent, of the weight of the fish.—in November they are no less than 23.3 per cent. In a fish of 30 lbs. in the spring they weigh about 120 grms.—in November they weigh over 2000 grms. The increase in the testes in the male is not so marked, but is sufficiently striking. In April or May these organs are about 0.15 per cent, of the weight of the fish, while in November they are 3.3 per cent. From what are these structures formed? As they grow, the muscle, as is well known, undergoes marked and characteristic changes. Not only does it diminish in amount as the season advances, so that the fish which have been some time in the river become smaller in the shoulder and back, but it loses its rich, fatty character, while it becomes paler in colour. Are these -changes in the muscle connected with the growth of the ovaries and testes? And if so, in what manner and to what extent? On the other hand, in fighting its way up rapids and over falls an enormous amount of muscular work is accomplished by the Salmon. Whence is the energy for this work obtained? Are the changes in the muscle connected with the performance of this work, and if so, to what extent are these changes connected with the muscular work, and to what extent with the growth of the genitalia? Lastly, the question arises, to what extent do these changes in the muscle modify the value of the flesh as a food stuff?