248 SALT-WATER FISHES 



cod, as well as {op. cit., pp. 74-78) a very interesting series 

 showing the egg-development. The barbel first appears when 

 the little fish is nearly an inch in length. Dull as are the 

 colours of the full-grown cod, some of the later larval stages, 

 an inch or two in length, exhibit great beauty of hue, with 

 burnished silver reflections and iridescent eyes. Small cod, 

 measuring from 5 to 10 in., are found in the algae on the 

 sea-bed, some of these being red in colour and others green, 

 doubtless to suit their surroundings. About a year after its 

 release from the egg the cod may measure a foot, and at that 

 stage of its career off it goes to the deeper water outside, 

 returning as a mature, grown-up fish in its third or fourth 

 year, its rate of growth being in the meanwhile apparently 

 little less remarkable than that of the salmon. 



Although it cannot too often be insisted that the growth 

 of fishes in captivity may furnish only an approximate clue 

 to their development under the more robust conditions of 

 nature, much interest attaches to such experiments as that 

 conducted by Captain Dannevig at Arendal, in Norway. 

 Here, in a large pond, he reared young cod, and studied 

 them for six months. They doubled the length at which 

 they emerged from the egg during the first fortnight. They 

 doubled their new length in less than another month, and 

 during the last four months that they were under obser- 

 vation they increased from a little over J in. to nearly 

 4^ in. Mcintosh and Prince found that young cod taken 

 at St. Andrews between the end of April and the beginning 

 of June measured -g- in., and the same observers also took 

 a larger stage, about double the length, with rays beginning 

 to appear in the fins. 



Young cod are said to require longer to hatch out, 

 conditions of temperature, etc., being equal, than those of 

 most other bony fishes. Thus, the cod takes from thirteen 

 to twenty days, whereas, in the same temperature, the 

 mackerel would require only six and the herring only nine. 



