1916 



Smith; on Salmon Development 



103 



PLATE 18 



Diagram of feeding ponds; A, B, the two ponds; a, water inlets; b, water 

 outlets; c, screens. 



The last comparison of the fish was made September 17. The fish 

 were taken as at other times by a random sweep of the net and carefully 

 dried on a linen towel. Table 15 gives the relative weight. In this com- 

 parison the fish from the dark weighed on the average 40.73 per cent 

 more than those from the light. 



Table 15. A comparison of the weights of fish taken Sept. 17 



Group 



No. of flsh 



Total weight 

 in grams 



Average weight 

 in grams 



The 12 largest and the 12 smallest were selected from each group 

 and weighed with the following results: 



The 12 largest from dark weighed 106.980 grams 



The 12 smallest from dark weighed 23.740 grams 



The 12 largest from light weighed 81.610 grams 



The 12 smallest from light weighed 16.320 grams 



The variation in growth had increased remarkably, the 12 largest from 

 the dark being 350.63 per cent heavier than the 12 smallest, while the 

 12 largest from the light were 400.06 per cent heavier than the 12 smallest. 

 The extreme variation in growth is shown by the weights and measure- 

 ments of the largest and smallest fish from eacli of these groups. Table 16 

 gives these determinations. The length in all cases was measured from 

 the tip of the snout to the base of the middle ray of the caudal fin. The 

 largest fish from the dark was but little less than eight times as heavy 



