134 



NATURE 



iDec. 8, 1887 



fish in-shore, local races might be formed ; but this is 

 taking for granted that during the process of incubation the 

 fish are brought under some remarkable spell which arrests 

 their strongly inherited instincts, and leads them to settle 

 down for life in the vicinity of their birthplace, instead of 

 roaming about to see the world like their free born cousins. 

 It seems, therefore, too much to expect cod and haddock 

 and other wanderers to remain always about our doors 

 because they happened to see the light under artificial 

 instead of natural conditions. But though fish-hatching 

 may not be able to influence much, if at all, the number 

 of fish in the open sea, and though it may not be able to 

 establish local races or shoals, it may still be of great 

 service. In the first place, it may be the means of intro- 

 ducing fish, which have the migratory instinct fairly well 

 developed, into waters where they practically did not 

 previously exist. For example, by instituting hatcheries 

 in the upper reaches of some of the long fjords in Nor- 

 way, a large school of haddocks or other round fish might 

 be readily created which might find all the conditions 

 necessary to their existence without wandering into the 

 open sea ; and, in fact, the same results might follow the 

 hatching on a large scale of round fish in some of our 

 own firths and bays. Again, as in America, it might be 

 possible to produce shoals of fish, such as the shad, 

 which, by wandering along the coast or living in the 

 estuaries, would be the means of attracting large and 

 .more valuable forms to the in-shore grounds ; fish, in 

 fact, which would act the part of the herring, but be a 

 more constant source of attraction — remaining in the 

 firths for several months at a time. Lastl}', fish-culture 

 may have a great future before it in hatching flat fish, 

 which have the double advantage of being extremely 

 valuable, while they are often very limited in their migra- 

 tions. The artificial hatching of sea-fish has not yet had 

 time to obtain a firm footing ; for the first trustworthy 

 experiments made were those of the German Commis- 

 sioners (Meyer, Mobius, and others), who hatched numerous 

 herring in 1874 in the Bay of Kiel. As is well known, 

 Norway has a Society for Promoting the Norwegian 

 Fisheries, with branches at the principal fishing centres. 

 In 1882 an experimental station under Captain G. M. 

 Dannevig was started at Flodevig, near Arendal, where 

 millions of sea-fish have been hatched, and a number of 

 cod and herring reared in a pond near the hatching 

 station. The question of hatching sea-fish is under 

 consideration at the present moment at Grimsby. It is 

 proposed to found a hatchery at Cleethorpes to propagate 

 round and flat fish, with a view of replenishing the ex- 

 hausted in-shore waters of the North Sea. Even should 

 this experiment prove unsuccessful, it will be of import- 

 ance in furnishing and spreading the technical education 

 and information so much required among those engaged 

 in the fishing industry. 



To successfully hatch sea-fish in large numbers, the 

 first and last requisite is an abundant supply of pure 

 sea-water. This necessitates a small sea-pond and a 

 number of large tanks, from which a constant supply of 

 pure filtered water can be readily obtained. In addition 

 to having at command an abundant supply of sea-water, 

 it is, of course, necessary to have the hatching-station in 

 the vicinity of some rich fishing-ground, where plenty 

 ripe fish may be obtained when wanted. 



Given plenty pure sea water and a number of ripe fish, 

 the next desideratum is a hatching apparatus, the form of 

 which must depend on the nature of the eggs to be 

 manipulated. While herring eggs are heavy, and not 

 only fall to the bottom, but adhere to whatever they 

 touch, the eggs of most of the food-fishes are non- 

 adhesive and lighter than sea- water, and hence they 

 float at or near the surface. Prof. Evvart describes and 

 figures a promisingly practical hatching jar for adhesive 

 eggs lately designed and used by himself, also the ap- 

 paratus used at Arendal for floating eggs, the most suc- 



cessful hitherto devised. With such apparatus it would be 

 possible, at a very small outlay, to hatch millions of float- 

 ing food-fish eggs, and thus to restore and maintain the 

 original productiveness of the in-shore fisheries. The 

 conclusion is that we ought to establish hatching stations 

 at one or more centres. One might be for round fish, the 

 other for lobsters and other shell fish. The Firth of 

 Forth and the Cromarty Firth seem admirably adapted 

 for the purpose, one great point being that minute pelagic 

 forms, such as the young fry feed on, are remarkably 

 abundant in both. A hatching station could be provided 

 for about ^tooo, and it is hoped the Board may soon 

 obtain a vote for the purpose. The hatching operations 

 at Flodevig, of the report of which Prof. Ewart gives an 

 interesting abstract, shows that many important practical 

 questions have been settled, and the conclusions reached 

 at Hovvietoun and elsewhere as to the influence of ex- 

 treme temperatures, sudden changes in the surroundings, 

 and also on the eggs and young spawn on full-grown fish, 

 have been well confirmed. 



Mr. Duncan Matthews gives (Part I.) a long paper, 

 excellently done, on "The Structure of the Herring 

 and other Clupeoids," with a series of capital plates ; also 

 Part II. of the " Report as to variety among the Herrings 

 of the Scotch Coast " ; notes on " The Food of the Whit- 

 ing," and on the " Ova, Fry, and Nest of the Ballan 

 Wrasse." Mr. R. D. Ciarkson's paper " On the Nutritive 

 Value and Relative Digestibility of White Fish" is as 

 interesting from the dietetic point of view as Mr. C. E 

 Fryer's suggestions for " The Preparation of Sprats and 

 other Fish as Sardines '" is from the economic. Prof. 

 Mcintosh reports on the work done last year at the St. 

 Andrews Marine Laboratory. The other scientific in- 

 vestigations include notes on " The Food of Young 

 Gadida?," and on " The Spawning of the Pike," by Mr. 

 George Brook; on " Entomostraca," by Mr. G. S. 

 Brady ; a paper on the " Development of the Common 

 Mussel," by Mr. John Wilson ; one on " The Physical 

 Conditions of the Water of the Firth of Forth," by Dr. 

 H. R. Mill ; and a " Further Report on the Examinations 

 of River- waters for Micro-organisms," by Prof. Green- 

 field and Mr. John Gibson. There are a number of 

 tables and plates which add greatly to the interest and 

 usefulness of the work. 



PROFESSOR A. WEISMANN'S THEORY OF 

 POLAR BODIES. 



ONE of the most noticeable features at the recent 

 meeting of the British Association at Manchester 

 was the manner in which naturalists of all nation- 

 alities agreed to do honour to Prof. Weismann, who 

 has contributed to theoretic biology in the last itv! 

 years with as lavish a hand as that with which he 

 formerly enriched the practical side of the science through 

 I detailed observation and far-reaching induction. 

 1 Ofhis later speculations upon the significance of obscure 

 I reproductive phenomena, the first ^ was abridged by Prof. 

 H. N. Moseley (Nature, vol. xxxiii. p. 154); while 

 perhaps the most important contribution to biological 

 I science at the Manchester meeting was an abstract of 

 I the newer pamphlet ^ recently reprinted in this journal 

 (vol. xxxvi. p. 607). The necessary limits of such 

 ! an abstract precluded any account of the obser- 

 vations which appeared to support Prof. Weismanns 

 views, as also of the details of the process by which, as he 

 supposes, the plasmata are removed in the polar bodies. 

 As neither the original pamphlet nor the still later 

 account of his observations upon parthenogenetic eggs 

 are generally accessible, it has been suggested that some 

 additional points, in expansion of the abstract, should be 

 given in these columns. 



' " Die Continurat des Keimpla'^ma'.s" Jena, 1885, 122 pages. 

 2 "Die Z-M der Richtuigsko.per," Jena, iSS;, 75 pages. 



