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instance he mentions, says, that a pair of salmon were observed in the Whittader, one of the tributaries of the Tweed, to be spawning on Nov. 2. The ova remains in the spawningbed or gravel for three or four months, according to Dr Fleming; according to Mr John Johnstone, from the ova deposited in November, December, and January, the young rise from the gravel in March, April, and May; according to Mr John Halliday, the spawn deposited in November, December, and the beginning of January, is disengaged from the spawning-beds from 10th March to 10th April; so that it appears, on an average of seasons, the salmon roe lies about four months, or 120 days, in the gravel beds before the young appear. But according to Dr Knox, in his single observation of the Whittader pair of salmon, the ova took 142 days "to become fishes somewhat less than an inch in length," but still "embedded in the gravel." (P. 473.) On the 19th of April the fry are "eight and even nine inches long ;" and on the 2d May they still abound in the tributary streams, but are not so numerous as before; they are not increased in size, and are, in all probability, the fry of a later deposit."-(P. 473.) So that the amount of Dr Knox's information here is, that the spawn of a single pair was hatched in April, and other families of other fishes were of a later deposit, and appeared in May. The witnesses examined before the Committee of the House of Commons had stated all this much more fully in 1824 and 1825. Thus, Sir Henry Fane says the fry descend in April and May Alexander Fraser, early in April and May-Rev. Dr Fleming, March, April, and May-Mr George Hogarth, jun., April and May-Mr William Stephen, March and April, to 14th May, according to the temperature of the season and the situation of the different rivers. It appears, therefore, that Dr Knox's single observation is corroborative of the evidence led before the Committee, as far as a single instance in a single river can; only it is to be observed, that he makes his single observation, made he says by himself, the rule for spawning in all rivers by all salmon, without reference to season or situation; while the evidence of practical men give the average result of many years of observation, extended over every variety of season,

and over all the rivers of the empire.

The mode in which the salmon deposit their ova in the gravelly bottom of shallow streams, is minutely described by Mr George Little (Report, p. 108-9), and, indeed, has been known for centuries; for John Monipennie has so long ago graphically recorded the manner in which this instinctive work is done. "In harvest," says he, "they come from the seas up in small rivers, where the waters are most shallow, and there the male and female, rubbing their bellies or wombs one against the other, they shed their spawne, which forthwith they cover with sand and gravel, and so depart away."-P. 195.

As to the developement of the ova under Dr Knox's "own immediate personal observation,"-though the ova would not, it appears, bear transmission to Edinburgh-it really seems unnecessary to notice such an evidently imperfect experiment, particularly since a very full and interesting account of the gradual developement of the ova of the salmon, accompanied by an accurate engraving, is given in the evidence of a gentleman before the Parliamentary committee. To that engraving, and the description of the report in general, I beg to refer any one who takes an interest in the subject. At the same time it is proper to mention, that there is an interesting article on the "Spawn of Salmon," by Mr Schonberg, printed in Sir David Brewster's Journal of Science in 1826, accompanied also by an engraving of the ova in different stages of growth. Both these sets of figures, and the accompanying details, correspond with one another in every essential particular; but both at the same time differ widely from the details given by Dr Knox. Neither does the Doctor even hint in his paper at the existence of such details or figures, though he could scarcely be ignorant of what is stated in the Report, which, he asserts, he had repeatedly read over.

To pass over discrepancies which materially lessen the value of his remarks, Dr Knox asserts, that "ova taken from the bed of a river at any time from January to March inclusive, and not shaken or carried far, will live and become developed, i. e. grow to fish of about an inch in length in a small glass full of water, changed not oftener than once a week," p. 476.

Then follows a passage in which temperature is said to have some effect in hastening or retarding the developement of the ova, though in his reckoning by days such agency is necessarily excluded; and he adds, that "after having cast the slough, they will live about ten days (seldom or never longer) in water unchanged, apparently thriving, growing, and darkening in colour (if exposed to the light) every day.”—P. 477.

This assertion, of the ova and salmon fry living a week and even ten days in a small glass of unchanged water (almost the only original observation in the paper) is in complete contradiction to all experiments that have been made on the developement of the ova of this genus of fishes. "It is said by Sir H. Davy" (says Dr Knox), "on the authority of a person of the name of Jacobi, whose writings I have not met with, that the ova of salmon are deposited in the gravel of rivers under streams, in order that they may be perfectly aërated, or exposed to water which is so. This reason, which appears so plausible, is probably not the true one."-(P.476). The person of the name of Jacobi here mentioned, though unknown to Dr Knox by his writings, was a Counsellor of State to the King of Prussia, and a well-known experimenter on the artificial fecundation of the ova of fishes. His experiments appeared in the Berlin Transactions for 1765, and have been referred to with approbation by almost every writer on the subject of fishes since. These experiments were made chiefly upon the ova of the genus Salmo; and he found that by expressing the unimpregnated ova in water, and afterwards applying the milt, the ova became impregnated, and went through the usual developement. In making these experiments, one thing essential to their success was found to be necessary, and this was the frequent, almost incessant, changing of the water; and hence he justly concluded, that the aëration of the water where ova are deposited, is necessary to the developement of the

ova.

Sir Humphry Davy, notwithstanding Dr Knox's gratuitous assumption of his incompetency to make observations on the generation of the salmon," had this experiment tried twice, and with perfect success; and it offers" (he adds) " a very good mode of increasing to any extent the quan

tity of trout in rivers or lakes." (Salmonia, p. 82). "In all experiments of this kind" (continues Sir Humphry)" the great principle is, to have a constant current of fresh and aërated water running over the eggs. The uniform supply of air to the fœtus in the egg is essential to life and growth; and such eggs as are not supplied with water saturated with air are unproductive."—Salmonia, p. 82, 83.

This necessary aëration, and exposure to the influence of the sun's rays, explains at once why salmon seek the gravelly bottom of shallow streams for the purpose of spawning; and the same instinctive impulse which guides the salmon, induces the herring and the cod, among numerous other fishes, to approach banks and shores, and thus carry boundless provision to countless animals. It was a curious circumstance in Jacobi's experiments, that the effect of his impregnation of the ova with the milt, often produced in the trout monsters with two heads, &c.-so different are the rude attempts of man from the instinctive workings of nature.

The experiments on the salmon ova by Mr Hogarth and Mr Schonberg, who both traced their developement, from the first appearance of life, till the animal was an inch in length, further demonstrate the necessity of this aëration. With "frequent changes of water, Mr Hogarth succeeded in hatching the ova, and by changing the water frequently' the animals appeared vigorous for three weeks, after which they became restless and uneasy.' (P.92). Mr Hogarth also tried one of the fry hatched in fresh water, if it would live in salt water; but found that it immediately showed symptoms of uneasiness, and died in a few hours.' (P. 92). The figures of the ova, and the young animal in its different states, were drawn by an artist, at the request of Mr Hogarth, and an engraving of them is appended to the Report of the Committee on the Salmon Fisheries.

Mr Schonberg found the frequent change of water equally indispensable. "Changing of the water" (says he), "and if possible from the same river. must be repeated hourly, and they must likewise be exposed to the sun's influence." (Journal of Science, v. 238). The developement of the ova is well represented in the engraving

which accompanies Mr Schonberg's valuable paper. The details of his experiments are more extended than those of Mr Hogarth; but both agree in all the more important points.

Dr Knox's experiment, although said to have been made under his own eye, is contradictory of the fact that aëration of the water is necessary, as he, or the person who took charge for him, appears to have kept the fry in water unchanged. But better evidence than this will require to be produced before we can give up the hourly and daily observations, bearing all the marks of truth, made by Mr Hogarth and Mr Schonberg, in opposition to the statements and examinations of Dr Knox or his assistants. Of Dr Knox's candour and fairness in not referring to the experiments of those gentlemen, though one of them appeared in the Parliamentary Report which he so much abuses, and the other in a Journal consulted by every one with any pretensions to science, I leave others to draw the inferences limiting myself to the plain statement of facts. Of course I hold, with all writers on the subject, except the author of this memoir, that the aëration of the ova by the frequent change of water is necessary to the developement of the salmon fry in rivers; and that this, and a certain exposure to the rays of the sun, influence the approach of fishes to the banks and shores upon which they deposit their spawn. In reference to Jacobi's experiments, the stocking of ponds or lakes with any desired species of fresh-water fishes, is, by these experiments, proved to be comparatively easy; for he found that the ova could be impregnated, and the animals from these ova hatched, after the parent fishes had been dead four days. Even the Vendace of Lochmaben might thus be introduced into other lakes without much danger of failure, by catching a few of these fishes previous to spawning. It is well known that the Chinese stock ponds with impregnated spawn of fishes.

The period of the salmon fry rising from their gravelly bed has been already stated generally as occurring in March, April, and part of May; but this of course depends upon the season. Mr George Little gives decided evidence as to this point. "A great deal" (says he)" depends upon the season at the time of the year,

whether we have an early spring or rot; sometimes there may be two or three weeks of difference, according to the season." "I have observed, when we have early warm weather, the fry come early, and when we have a late spring, it is later before the fry rise from the gravel bed." (P. 109).

The descent of the fry to the ocean is, in the Avon, according to Sir Henry Fane, in April and May-in the Ness, according to Alexander Fraser, early in April and May-in the Don, March and April, to the middle of May-in the Dee, April and Mayin the Tay, March, April, and May; and so on, according to the season. The kelts, or spawned fish, descend with the winter and spring floods. But the dates given in evidence by the numerous and respectable witnesses examined before the committee are not be taken as absolute periods, common to every year. The temperature of the season must be a powerful element in determining the ascent of the salmon, the deposition of the ova, and the hatching of the ova; in fact, the temperature and other eircumstances, there is every reason to believe, might have the effect of hastening or delaying the process of reproduction, as the same meteorological agents are known to hasten or retard the annual harvest, or prematurely bring out or delay the appearance of many of the insect tribes. With the exception of Dr Knox fixing a determinate period for the developement of the ova in the gravel till the appearance of the smolt, I say, with this exception alone, any reader of his paper, and the minutes of evidence, might have naturally enough supposed, that, with regard to these points, he took his information from the Parliamentary Report, which he reprobates, and from the testimony of witnesses whom he declares unworthy of all belief; and the strong coincidence between the Doctor's periods of migration as related in the Transactions, and what was stated by these gentlemen six years before, must either appear very strange, or the witnesses have not deserved that unmannerly abuse which has been dealt out to them under the sanction of the Royal Society of Edinburgh.

Another particular noticed by Dr Knox in his observations upon the salmon smolts is, that they will not

bear the slightest handling-they

constantly died in a short time after being touched.”—(P. 481.)-And then the Doctor expresses his "surprise when" (says he) "we read of smolts caught" (it is not said how, but it matters not)," and after being, according to all accounts, rather roughly handled, and even mutilated by the amputation of a fin, replaced in water, and arriving at mature years as a full grown salmon ; we are, we repeat" (continues the Doctor), "left in wonder at the amazing contradictions between such observations and those we have personally made, observing every possible care." (P. 482.)

This passage only proves Dr Knox's awkwardness, or the deadly nature of his gripe; for no one point in the natural history of the salmon is better ascertained than that they survive the mutilation of a fin, and even live years with a ring round their body, close to the tail. Thus Mr William Stephen says in evidence, "we have marked fry going down, and have got them that season as grilses, and in the following season we have got them as salmon."-Report, 1828. Mr George Hogarth marked a number of smolts in the month of May, by cutting off the mort fin; in the course of the month of June, several of these, grilses, were found without that fin; in this year (1825) there have been already got three salmon marked in the same way.-Report, 1825, p. 92. And Mr Murdoch Mackenzie marked a grilse kelt in the month of March, 1823, in the river Oykell, by tying a piece of wire round the body of the fish, immediately above the tail; and in March, 1824, the same fish was caught as a salmon in the same river.-(Report, 1825.) But these experiments were made by the provoking people who have forestalled all the Doctor's discoveries, and anticipated him in every point of the salmon's history, and who are, therefore, on that very account, unworthy of belief.

A still more particular experiment is, however, related in the Highland Society Transactions, Vol. ii., by Mr Alexander Morrison. "In May, 1794" (says Mr Morrison), " I marked five smolts in the presence of five fishermen, and in such a manner, that if ever any

of them returned to the river, and were caught, no doubt could remain as to their being of the number so marked. Two of these smolts, then become grilses, I caught in six or seven weeks after they had been marked, when they weighed about 3 lbs. each. In the month of April, 1795, I caught another of the number, then a salmon, which weigned between 7 and 8 lbs. ; and in the month of August of the same year I caught a fourth, weighing 8 lbs."-P. 391.

But in case the author of the paper may object, that all these experiments were made and related by men not known to the world as scientific, I shall add to their testimony that of an illustrious naturalist, Lacepede, who, in stating the curious fact of salmon ascending the particular rivers in which they were hatched, thus writes: "It is worthy of remark" (says he) "that salmon return every year to the place where they were spawned, as swallows return to the buildings where they formerly had their nests. The physician Deslandes bought twelve salmon at Chautelain, a small town upon our coast, near to which they capture to the amount of 4000 salmon per annum. He attached a ring of copper to the tail of these salmon, and then restored them to liberty. Five of these fishes were retaken the following year, three the second year, and three others in the third."-Lacep. Son. Buff. xii. 133.

The history of the salmon, as detailed in the evidence before Parlia ment, and by writers on natural history, may be told in a few words. Impelled by instinct to ascend the various rivers for the purpose of spawning, at a certain period of the year, they reach the remotest streamlets, where their ova may be deposited in safety, and the young, when hatched, find their food. When this purpose is accomplished, they return again to the sea. The same instinct guides the fry, when of a certain age, to fall down their native streams to the distant ocean, there to remain till the imperative call of nature for reproduc. tion impels them to seek again the places of their birth. It is not ascertained satisfactorily whether salmon

From experiments now in progress by Mr Shaw, Dumfries-shire, he is led to believe that the salmon fry do not leave the rivers or descend to the sea in the year in which they are hatched. Mr Shaw is even inclined to believe that they remain two years in fresh water before descending to the ocean.

ever ascend rivers beyond the tideway for any other purpose than that of spawning. The practical inference to be drawn from such facts is, that the fishery of salmon should cease, and the animals be protected while spawning or seeking the spawning-bed." But as this period varies with the seasons, and the situation of the different rivers, and as, moreover, all the species do not come into full roe at the same time, the close time, so far as legislative enactments can do so, must be regulated by periods fixed arbitrarily on the knowledge of the general habits of the salmon, when the greatest numbers are observed to ascend the rivers, and the greatest number of spawned salmon and smolts descend to the sea. To prohibit the fishery in every month in which salmon are observed to ascend and descend, would narrow the period of fishery without perhaps any equivalent advantage. The general migration of the mass, it is evident, ought alone to regulate this close time; and there is full and satisfactory in formation as to these periods, in the evidence led before the Parliamentary Committee in 1824 and 1825. Protection in the rivers for the ascending fish, and till they have spawned and returned to the sea, is absolutely necessary to insure the deposition of a sufficient quantity of the spawn; and this protection secured, there is no fear of an abundant supply. The natural increase of the salmon, did not human ingenuity limit that increase by the destruction in every shape of the spawning fish that ascend the minutest streams, is quite equal to support the devastations which may be committed on their ova or fry by enemies in their own element. According to Mr George Little, there are in a salmon 17,000 ova, and in a grilse 10,500 at an average; and, according to Bosc, 27,850 ova have been found in a salmon of 20 lbs. weight. Even the angler, under certain restrictions, would not be able materially to abridge the number of the young, produced, as they would be, if the spawning fish were protected, in myriads, and wafted to the ocean in shoals which might feed a whole people. It is only the wholesale destruction of the adult salmon, when ready to spawn, and when it ascends the rivers for this purpose, that obstructs the habitual fecundity of nature; and it is only the uncontrollable impulse of instinct, acting

against all opposition, that preserves the present supply. Were not the salmon one of the most prolific of fishes, its fishery on our coasts would soon cease to be of value.

As not at all connected with the subject of these observations, I pass over the uncalled-for attack upon Dr Paley and our celebrated associate Sir Charles Bell, in page 499. I only remark, that, in Dr Knox's paper, the reader will in vain look for inferences, drawn from the circumstances detailed, of the wisdom and beneficence of that Great Being, who directs the migrations of fishes, and teaches them, with unerring aim, to deposit their ova where the young, when hatched, are sure to find a supply of food.

I have, I trust, satisfactorily demonstrated, that the food of the herring and salmon was known and described long before the appearance of Dr Knox's paper in the Transactions of this Society: That the food of the herring, in the first place, was well known and described by Neucrantz, by Leuwenhoek, by Müller, by Fabricius, by Bloch, and mentioned by Lacepede, by Bosc, Latreille, Pennant, Turton, Scoresby, MacCulloch, and many others-indeed by almost every person who has written upon the natural history of the herring. And that, in the second place, the food of the salmon, in rivers and in the sea, its periodical ascent of rivers for the purpose of depositing its spawn, the developement of the ova, and the descent of the fry to the sea, were all perfectly well known, in every particular, before the year 1833, is equally manifest, from the facts and authorities I have mentioned.

I trust I have not, in attempting to do justice to the claims of the illustrious men who have written upon this subject, and in my remarks on Dr Knox's paper, gone beyond the limits of fair criticism. I should be sorry, indeed, if I was considered to have failed in the courtesy due by one member of this Society to another. But there were statements which, in treating of the subject, I was bound to contradict-there were claims of discovery to be disproved by the statement of prior discoveries-and if the author of the Memoir has appeared to disadvantage in the comparison of rights, it was a situation of his own choosing.

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