BBITISH, COLONIAL AND OTHEB COBBESPONDENCE, ETC. 587 



Christiania, and have resulted in some unexpected discoveries. The 

 seas in the neighbourhood of the Loffoden Islands on the coast of 

 Norway had long been known to be a great place of resort for cod 

 during the spawning season ; and in 1864 Professor Sars commenced 

 his work there, and by means of a small surface towing net he ob- 

 tained plenty of the ova of the common cod (Gadus morrhua) float- 

 ing at the surface; examples in various stages of development were 

 procured, the young fish were successfully hatched out, and the species 

 identified beyond a doubt. Subsequent observations fully confirmed 

 the accuracy of the conclusions previously arrived at that the cod 

 spawn was not deposited on the ground but floated freely at or near 

 the surface. In 1865 the same observations were made on the ova 

 of the haddock (Gadus aeglefinus), and it was satisfactorily proved 

 that they went through all their stages of development while floating 

 at the surface, in precisely the same manner as in the case of the cod. 

 Sars was at first inclined to believe this development of the ova while 

 floating was peculiar to the members of the Gadidae or cod family, 

 in its restricted sense ; but in the summer of 1865 he visited the south- 

 ern coast of Norwav during the season for mackerel, and found 

 abundant evidence of the same rule obtaining in that widely distinct 

 fish. In the case of mackerel, the spawning actually takes place at 

 the surface; but with the cod family we believe the operation has 

 not been so distinctly observed. The ova, however, are undoubtedly 

 met with at the surface and at a short distance below it. Entirely 

 subversive as these discoveries of Professor Sars* are of the popular 

 notions about fish-spawning, it is even more unexpected to find that 

 both he and M. A. W. Malm of Gothenburg have independently 

 ascertained that the ova of that essentially ground-fish the plaice 

 (Pleuronectes platessa) follow the same rule of floating at the sur- 

 face. Other kinds of floating ova were also obtained by Sars, some 

 of which he succeeded in hatching; arid he has completely identified 

 the gurnard (Trigld) and the garfish (Bellone], in addition to those 

 before mentioned. It is evident, then, that the floating of fish ova 

 during the development of the embryo must be taken as the general 

 rule in several large and distinct families of sea fish. Sars has 

 pointed out that the development takes place at the bottom in the case 

 of those fishes especially whose ova are cemented together by a 

 glutinous secretion, or fastened in lumps to foreign bodies, such as 

 Algae, Hydroida, etc. He mentions as examples of this, among 

 others, the herring (Clupea), the capelin (Osmerus), the species of 

 Coitus, Liparis, etc. 



It is particularly worthy of notice that, according to these observa- 

 tions of the Norwegian naturalists, all the important kinds of fish 

 taken by our line fishermen and beam-trawlers, and the mackerel 

 among such as are caught by the drift-nets, may be reasonably in- 

 cluded among the species whose spawn floats at or near the surface of 

 the sea, and their ova cannot therefore be liable to the slightest injury 

 by any method of fishing which is carried on upon or near the ground. 

 For if that be the rule with the spawn of the cod and haddock there 

 can hardly be a doubt about its being so likewise with the ova of 

 ling, coal-fish, whiting, pollack, hake, and that northern species, the 

 tusk, all belonging to the same family. Again, turbot, halibut, brill, 

 soles, plaice, dabs, and flounders are all closely allied, and there can 

 scarcely be a doubt that the same rule applies to all which Sars and 



