672 



NATURE 



[October 29, 1908 



purpose can be served by merely writing to the effect 

 that the proper way of solving the problem of flight 

 is by means of vertical screws or by imitating the 

 action of birds' wings. \\'hen people can fly for an 

 hour by one method they will scarcely be likely to try 

 another. An actual demonstration of either of these 

 alternative methods as applied to a man-carrying 

 machine would, of course, be watched with consider- 

 able interest. Whatever may be the best and cheapest 

 way of advancing aeronautical knowledge, it is prob- 

 able that the human element and the feeling of " every 

 man his own fiving-machine " will appeal most to the 

 Englishman, and more scientific methods will appeal 

 more to the German, who has already arranged for 

 translations of Mr. Lanchester's works. 



Mr. Herbert Chatley ' has directed attention to the 

 part plaved bv eddv formation in determining the flow 

 of air in the wake of aeroplanes. This factor may 

 introduce dangers in a fiving-machine should the rate 

 of eddv formation coincide with the period of free 

 oscillation. Accidents from a similar cause have 

 frequentlv occurred in other branches of engineering, 

 and it seems very probable that some day we shall 

 have an object-lesson of the kind in aeronautics. But 

 the study of these eddies affords an interesting re- 

 creation for those who like to look into the matter. 

 The side of a ship is a good place for watching eddy 

 formation, but a better place is a dusty road along 

 whicli motor-cars are passing. Here anyone can see 

 the eddies being thrown off at perfectly regular in- 

 tervals, each picking up a separate cloud of dust and 

 whirling it high into the air. If the observer cared 

 to carrv his researches further he might get a motor- 

 car, and trv attaching tails of different sizes and 

 shapes to it until he got one in which the eddy forma- 

 tion was reduced to the smallest possible amount, and 

 the air resistance would probably be also red'jf.-.l. 

 He would not succeed in abolishing dust altogether, 

 nor would he make a fortune by talcing out a patent ; 

 but he would discover a more effectual means of re- 

 ducing the dust nuisance than by writing complaints to 

 the newspapers. G. H. Bryan. 



MARINE BIOLOGY. 

 '■pHE work of the Danish naturalists on behalf of 

 ■'■ the International Commission for the Investiga- 

 tion of the Sea is greatly enriching our knowledge 

 of the natural history of important sea-fishes. In 

 " Serie Fiskeri," Bind ii., Nos. 5-8, of the Danish 

 *' Meddelelser fra Kommissionen for Havunders^- 

 gelser," there are several important papers by Dr. 

 Johs. Schmidt, a naturalist well known for his dis- 

 covery of the breeding-places of ihc common eel of 

 European rivers. 



In No. 6 Dr. Schmidt records the results of marking 

 experiments with plaice and cod in the waters around 

 Iceland. Of numerous mature plaice caught, labelled, 

 and liberated in the summer of 1905 off the north 

 and east coasts respectively, those re-captured of the 

 former batch were found to have travelled west- 

 ward, the latter southwards along the east coast 

 and then westwards along the south coast, taking 

 in each case the shortest route to the zvarm Atlantic 

 waters. Here in winter and spring they spawn. 

 The eggs and fry are then carried passively along 

 by the Atlantic stream (Irminger current), which 

 sets eastwards in spring and summer, and the just- 

 transformed young appear successivelv in the bays 

 and fjords, first on the west, later on the north, and 

 later still on the east coast. Immature cod, caught, 

 labelled, and liberated at the same time as the plaice 

 on the north-east coast, did not migrate, but remained 



^ .4cfVfiaii/ics, Augusl, igoS. 



xo. 20 



OO) 



VOL. 



f8] 



on that coast tltroughout winter, and even for one to 

 two years after liberation. It was also found that 

 one-year-old cod were much more numerous on the 

 east coast than on the south and west. On the other 

 hand, the eggs of the cod was absent in hauls with 

 pelagic nets made on the north and east coasts, but 

 plentiful on the west and south. From these facts it 

 appears that the peculiar hydrographlcal conditions 

 round Iceland involve a double migration .of con- 

 siderable extent on the part of cod and plaice, viz. 

 (i) the passive drift with the eastward-setting Atlantic 

 stream of eggs and fry born off the south and west 

 of the island; (2) the active return migration of spawn- 

 ing fishes to the warm water, due to their special sensi- 

 tiveness to external conditions on the approach of the 

 spawning season. 



.\nother noteworthy result of these marliing experi- 

 ments is to show that Iceland plaice grow at an aver- 

 age annual rate of 2-3 centimetres, much slower, 

 therefore, than in the North Sea. The most obvious 

 cause of this is the low temperature of the water, 

 on the east and north coasts especially, and the short 

 summer. It is also interesting, from the practical 

 fishery standpoint, to note that more than 60 per cent, 

 of the re-captured marked plaice were taken by 

 English steam trawlers. 



Hitherto the post-larval stages of those North 

 .\tlantic gadoids, viz. the hake (Merhiccius vulgaris), 

 Molva elongata, and Rauiceps raninus, have not been 

 described or figured in literature. In No. 7 Dr. 

 Schmidt gives descriptions and figures of thirteen 

 different post-larval stages of the hake. .\11 these 

 were carefullv identified with the adult by counting the 

 numbers of vertebra; and fin-rays. The paper also 

 contains a summary of the distinctive characters of 

 various gadoids in the post-larval stage. 



In No. S there are described seven different post- 

 larval stages of Rauiceps raninus, a remarkable- 

 looking plump form, somewhat resembling a post- 

 larval Liparis species, and differing from other post- 

 larval gadoids in not possessing the usual three post- 

 anal bars of pigment. In this number also are 

 described and figured four different post-larval stages 

 of Molva elongata and Molva byrkelange. These two 

 forms, in regard to which Holt and Byrne thought 

 " a single species was enough for the reception of 

 both," are shown to have perfectly distinct post-larval 

 forms with characteristically different arrangements of 

 pigment. The geographical distribution of the two 

 forms, as Dr. Schmidt points out, is also quite dif- 

 ferent, so that there can now be no doubt that we 

 have to deal with two species. 



In No. 5 Ove Paulsen describes and figures all the 

 species of Peridiniales so far known to occur in Danish 

 waters. The Peridiniales are a most important group 

 of unicellular organisms from the standpoint 'of the 

 student of plankton, since certain species of them 

 appear to be characteristic of water of neritic and 

 oceanic origin respectively. The descriptions appear 

 to be adequate, and there are usually figured several 

 different views of each form. There is also a copious 

 list of literature at the end. 



NOTES. 



At the general meeting of the Royal Society of Edin- 

 burgh, held on October 26, Sir William Turner, K.C.B., 

 F.R.S., was elected president of the society. 



The King has granted his Royal licence and authority 

 to Dr. Ludwig Mond, F.R.S., to wear the decoration of 

 the Grand Cordon of the Crown of Italy conferred upon 

 him. 



