Dec. 24, 1 8 74 J 



NA TURE 



151 



electricity in accordance with Weber's law had not yet 

 been discovered. And if some one else takes this 

 trouble, then he who considers himself a representative 

 kot' t^oxhv of the deductive method should applaud him, 

 instead of charging him with impiety, even if the results of 

 the inquiry should turn out to be inconvenient for the 

 Icarus flight of speculation. 



As Mr. Zollner does not put himself forward as a mathe- 

 matician — on the contrary, informs us on pages 426 and 

 427 of his book that the too frequent use of mathematics 

 cramps the conscious activity of the understanding and 

 is a convenient means of satisfying vanity ; and besides, in 

 many passages, constantly repeats his expression of con- 

 tempt for those who think they can refute his speculations 

 by pointing out mistakes in differentiation and integration 

 — we ought not to judge him too severely in the matter 

 of Weber's law. No doubt it is scarcely reasonable for 

 one who thinks himself entitled to be shaky in his mathe- 

 matics, to take upon himself to pronounce upon iiiattcrs 

 which can be decided by mathematical investigation 

 only. His " Theory of Comets," which may surely be 

 regarded as in his opinion a model specimen of how the 

 right methods are to be employed, gives, besides this, 

 other much more popular examples of the same peculiar 

 way of using or not using deduction, examples the con- 

 sideration of which may be reserved for another more 

 suitable opportunity. 



{To be continued.) 



MOVEMENTS OF THE HERRING 



THE mysterious disappearance of the body of herring 

 which used to frequent Loch Fyne has directed re- 

 newed attention to the natural history of that fish. This 

 is now the second time that the shoal of herrings which 

 made Loch Fyne its halutat has deserted that celebrated 

 sheet of water. No scientific opinion has yet been given 

 as to the cause of this disappearance. A number of 

 fishermen, resident on the Loch, say the herrings have 

 been frightened away in consequence of persons fishing 

 for them with a trawl net— which is, of course, non- 

 sense ; but not more nonsensical than the reasons 

 assigned for the desertion by herring of other locali- 

 ties. As the so-called trawl-fishing of Loch Fyne (the 

 net used is in reality a seine) was not in existence when 

 the fish forsook the Loch on a former occasion, and 

 were absent for a period of six years, the opinion of these 

 men may be passed over as unworthy of serious con- 

 sideration. Writers in the local newspapers, while in- 

 clined to favour the opinions of the drift-net men, that is, 

 those who assert that the trawl-fishers have scared away 

 the fish, also ask whether the spawning-beds may not 

 have been in some way interfered with, and whether the 

 body of fish frequenting the Loch may not from some un- 

 known cause have departed before depositing their seed. 

 If so, in what year would that occur ? In other words, how 

 long is it before the herring spawn of any given year 

 comes to fife, and at what period will the fish then born 

 become reproductive ? 



These are events in the natural history of the herring, 

 the dates of which have not yet been authoritatively 

 settled. They are points, indeed, which have not yet 

 been decided as regards any of our fish, except, perhaps, 

 the salmon {Salino sala)-), which has been nursed into life 

 under a system that may be called artificial, that ad- 

 mitted of the young fish being watched, and their growth 

 traced stage by stage, by means of certain signs and marks. 

 It is thought that we may speak of the natural history of 

 the salmon with more confidence than that of any of our 

 other food-fishes. It is unfortunate that their studies of 

 the natural history of the herring have not yet enabled 

 naturalists to determine with exactitude how long it takes 

 that fish to come to maturity. 



Most varied opinions have been given on these points 

 of herring life. Some persons have even gone the length 

 of asserting that Clupca /lariiij^Hs and its congener Clupca 

 pilchardiis are able to perpetuate their kind within a 

 year of their birth ; even at the age of ten months ! It 

 has also been asserted that a herring is able to breed 

 twice a year. Other opinions have been given, which 

 assign to the herring a much longer period of growth, 

 namely, that it requires from three to five years to reach 

 maturity. Yarrell, again, and also Mitchell, think that it 

 becomes reproductive in so short a period as eighteen 

 months. What we may hold that we really do know is, 

 tliat the eggs of the herring; can be hatched within twenty 

 days after their contact with the milt of the male fish. 

 This has been proved by visiting the spawning places 

 of the animals. On one visit all was spawn, everything 

 that came in contact with the spawning-beds being covered 

 with the seed of the herring ; at the next visit, a fortnight 

 after, the spawn was all gone ; it had become vivified— and 

 in proof of the fact, young herrings could in two or three 

 weeks after be found in shallow places varying from an 

 inch to two and even three inches in length. The 

 probable time between the spawning of the fish and the 

 fry reaching the dimensions named would be about forty 

 days. How fast the young ones grow after that has not 

 been authoritatively ascertained. It is thought, however, 

 that if young herring reach the size of, say two-and-a-half 

 inches, in forty days, it is not unreasonable to expect them 

 to continue growing at the same ratio. 



In the case of Salino sa/ar, the period necessary for 

 the incubation of the egg has been determined beyond 

 dispute. It ranges from 90 to 130 days. The growth of the 

 young fish, after a time, if those who have watched it have 

 not been deceived, is very rapid. At first, however, the 

 salmon grows very slowly. A salmon hatched in March 

 last may still be a very tiny animal, even after it is twelve 

 moiiths and in some cases two years old. In a year, 

 however, it may be four or five inches long, and ready 

 to migrate to the sea. There is a curious feature in the 

 natural history of the salmon, the law of which has never 

 yet been discovered— it is a riddle, in fact, even to the 

 most scientific observers : only one half of the salmon 

 of any particular hatching develop into what is called the 

 s/no/f, or migratory stage, at the end of about twelve 

 or fifteen months from the time of their being hatched. 

 The other moiety of the brood does not seek the sea 

 or take on the migratory dress till the expiry of a little 

 over two years from the time of birth ! One half of 

 the fish, therefore, will at one and the same time be tiny 

 creatures, about three inches long, whilst the other moiety 

 will be five inches in length, and of cerresponding girth ; 

 but these dimensions, it must be confessed, show no great 

 rapidiiy of growth. Indeed, it is not till after the salmon 

 proceeds to the sea that its growth becomes at all rapid ; 

 but, notwithstanding this rapidity, it must, we think, be a 

 considerable number of years before a salmon can attain 

 to the weight of fifty or si.xty pounds ; although the smolt, 

 it is affirmed by those who have watched it, returns as a 

 'grilse to its native waters in about three months, its size 

 and weight being very largely increased. 



The herring, as we all know, is a fish that never attains 

 to any great size, and the weight of which may be counted 

 in ounces. The question to be answered is this : Do small 

 fish grow to maturity quicker than large ones.' It has 

 been asserted, m some quarters, that the herring grows 

 quite as rapidly as the smolt does a/ii-r it reaches the 

 salt water, and the rate of growth there appears magical, 

 when contrasted with its slow progress during the first 

 year of its existence, or it may be, as has been already 

 explained, the first two years. We are not, however, 

 without a certain kind of proof of the rate at which the 

 herring grows, which is better than reasoning analogically. 

 It is quite fair to conclude that if herrings attain a size of 

 about three inches within forty days or so of their birth , 



