Ill] THE GROWTH OF WHALES 175 



they do not seem to be increasing, though at 84 ft. they still have 

 another 10 feet or more to grow. They may grow slower, and live 

 longer, than is often supposed*. 



On the other hand, if we draw from the same official statistics 

 the mean size of mother-whale and foetus at some given epoch of 

 the year (e.g. March 1934), there appears to be a marked correlation 

 between them, such as would indicate very considerable growth 

 of the mother during the months of pregnancy. The matter deserves 

 further study, and the data need confirmation. 



Blue whales; length of mother and foetus {March 1934) 



341 



On the growth of fishes, and the determination of their age 



We may. keep a child under observation, and weigh and measure 

 him every day; but more roundabout ways are needed to determine 

 the age and growth of the fish in the sea. A few fish may be caught 

 and marked, on the chance of their being caught again; or a few 



* The growth of the finner whale, or common rorqual, is estimated as follows 

 (Hamburg Museum) : at birth, 6 m.; at 6 months, 12 m. ; at one and two years old, 

 15 and 19 m. ; when full-grown, at 6-8 ( ?) years old, 21 m. For data, see Hvalradets 

 Skrifter and Jhtemational Whaling Statistics, passim ; also N. Mackintosh and others 

 in Discovery Reports; also Sigmund Rusting, Statistics of whales and whale- 

 foetuses, Rapports du Conseil Int. 1928; etc. 



