1916 



Smith; on Salmon Development 



101 



weighing. The average weight of those from the dark trough was .9002 

 gram and of those from the light trough .7729 gram. Those from the dark 

 according to this determination weighed 16.47 per cent more than those 

 from the light. This weighing gives a smaller average difference than the 

 last estimate. 



No weight determinations were made between April 7 and May 20. 

 On the latter date 307 fish were taken from the dark trough and 208 from 

 the light. Both groups were preserved in formalin and after two days 

 they were dried as uniformly as possible and weighed. Table 12 gives 



Table 12. Comparison of weights of fish taken May 20 



the results of this determination. Comparing the average weights, one 

 finds the fish from the dark were 18.94' per cent greater than those from 

 the light. 



Twenty-eight fish were picked at random from each of the groups 

 taken May 20. Measurements of their length and greatest depth were 

 made. Tables 13 gives the maximum and minimum dimensions between 



Table 13. A comparison of the dimensions of 28 fish from each group 



in table 12 



which they varied, also the average for each group. An increasing dif- 

 ference in dimensions between the two groups of fish is noticeable. The 

 twenty largest and the twenty smallest fish were picked from each group 

 and weighed with the following results : 



The 20 largest from dark weighed 41.010 grams 



The 20 smallest from dark weighed 22.320 grams 



The 20 largest from light weighed 38.360 grams 



The 20 smallest from light weighed 14.240 grams 



The 20 largest from the dark trough weighed 83.7 per cent more than 



the 20 smallest from the same trough, while the 20 largest from the light 



trough weighed 169.4 per cent more than the 20 smallest from the same 



