42 American Fisheries Society 



survivors, and continued for another twenty-one days. During 

 this time the excreta were collected and analyzed five times. A 

 short fast of four days intervened between the first and second 

 part of this experiment. The composite weight of the five finger- 

 lings was 34.8 grams, and these increased 11.3 grams in the 

 twenty-one days, or considering the average weight at the begin- 

 ning and closing of the entire experiment, the finger lings gained 

 about 66 per cent in weight. 



By reviewing the data pertaining to the second part of the 

 experiment, certain differences will be observed as compared with 

 the results obtained in the first part, which to a certain extent 

 substantiate the experience gained in the preceding experiment 

 000.5. 



In the first place the ratio of dry feces to the dry matter of 

 food is 50 per cent higher, and this increase in the fecal discharge 

 runs parallel to the diminished utilization of the nutriment. 

 The conclusion, therefore, is warranted that in this instance also 

 the digestive activity was somewhat impaired by the short fast. 

 The growth capacity, was not affected in this instance, the finger- 

 lings having grown more in the three weeks following the fast 

 than during the twenty-six days preceding it. The gain in weight 

 represented 49.8 per cent of the quantity of food per day and 

 kilogram, as compared with 42.7 of the earlier period. 



Two things must be borne in mind in connection with these 

 experiments: In both instances the evidence clearly indicates 

 that fasting is deleterious to the digestive function of the trout. 

 The difference in effect upon subsequent growth may probably be 

 due to the fact that in experiment 000.5, the intervening fast was 

 a much more protracted one. 



The last experiment on the effect of feeding raw beef heart is 

 particularly interesting, as this was performed on the trout which 

 had undergone a preliminary fast (F-l). In the course of fifteen 

 days of the experiment, this trout consumed 27.71 grams of food 

 with a content of 7.047 grams of dry matter. Examining the last 

 three vertical columns of Table IV, the thing which strikes one's 

 attention at once is the high proportion of fat in the feces; then 

 the apparent retention of nitrogen as is shown by the low nitrogen 

 content of excretions passed during the first several days after 



