AT THE PLYMOUTH LABORATORY. 



311 



(1) . . 



(2) . . 



(3) . . 



(4) . . 



It must, however, be mentioned that the weight given for the last 

 fish, 51b., is inconsistent with a subsequent test two months later, in 

 which the heaviest fish weighed 4 lb. 8 oz. There is no ground for 

 supposing that an error occurred in the reading, but it is difficult to 

 understand such a loss of weight in the interval, and it is safer to omit 

 these four weights in considering the average rate of growth. 



It was subsequently decided by the Duke of Bedford that as little 

 information was likely to be added by retaining the salmon any longer 

 at the Laboratory they should be liberated. On August 20th, 1908, 

 the remainder were therefore marked and turned out into the sea, out- 

 side the Plymouth Breakwater. Some of them were already showing 

 signs of approaching maturity for the third time, and in one of them 

 that died before being liberated the ovary was much developed. In- 

 cluding this last individual, the weight of these eleven fish at this 



date was as follows : — Wftght Length. 



inches. 

 17 

 19 

 19 

 19 

 20 

 21 

 21 

 21 

 21 

 21 

 22 



giving an average weight of 3 lb. 9| oz., and an average length of 

 20 inches. 



Summarizing the above data, the following show the averages of 

 growth at intervals, during the period of about two years and a half, 

 in which the salmon were kept at the Laboratory : — 



