REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



29 



The fact which this experiment brings out cleariy is that the pro- 

 portionate growth becomes less rapid as the clams get older and 

 larger. The 1902 set (nine months old at the beginning of the ex- 

 periment) have gained 160 per cent, of their length, while those a 

 year older gained, under the same conditions, 36.4 per cent, of their 

 length, and those very old clams have scarcely increased at all, gain- 

 ing only 3.7 per cent. 



In the same experiment some of the clams were divided into groups 

 according to size, disregarding the age. The average increase in 

 sample specimens of these six different groups on several dates are 

 given in the following table : 



AVERAGE MEASUREMENTS. 



AVERAGE MEASUREMENTS. 



Selected Sizes. 



Over 3 inches 



Between 2J and 3 inches. 

 Between 2 and 2J inches. 

 Between H and 2 inches. 

 Between 1 and IJ inches. 

 Between ^ and 1 inch. . . 



Feb. 20, 

 1903. 



Average 



original 



size. 



79.0 

 66.8 

 53.8 

 47.7 

 28.1 

 21.8 



September 10, 

 1903. 



Average size. 



mm. 



82.0 

 73.9 

 65.0 

 63.6 

 56.0 

 47.0 



inches. 

 3i 



2ii 



2A 



2i 



21 



Feb. 20, 

 1903. 



Average 

 original 



77.0 

 68.7 

 53.2 

 46.6 

 28.0 

 21.8 



October 20, 1903. 



Average size. 



82.0 

 76.5 

 70.6 

 69.0 

 64.8 

 59.3 



inches. 



3i 



3i 



ol 3 

 ■^T6 



2i 

 2i 



