10 



BULLETIN 649, U. S. DEPARTMENT OF AGRICULTURE. 



Denis x in a study of the blood of a number of fishes found urea in 

 the blood of the grayfish. An analysis of the canned grayfish showed 

 that the flesh of this fish contained both ammoniacal and urea 

 nitrogen. The amount of nitrogen present in this form is, however, 

 relatively small, and when allowance was made in the experiments 

 which follow for this nonprotein nitrogen it was found that the 

 value for the coefficient of digestibility of protein was not materially 

 changed. 



Eight digestion experiments have been made with the grayfish 

 and the results obtained for the three-day test period are reported in 

 the following table: 



Data of digestion experiments with grayfish in a simple mixed diet. 





Weight 

 of food. 



Constituents of foods. 



Experiment, subject, and diet. 



Water. 



Protein. 



Fat. 



Carbo- 

 hy- 

 drates. 



Ash. 



Experiment No. 535, subject H. R. G.: 



Grams. 



1,409.0 

 486.0 

 400.0 

 581.0 



Grams. 

 971.2 

 366.9 

 27.6 

 491.5 



Grams. 



244.3 



12.1 



32.4 



2.3 



Grams. 



160.8 



0.5 



53.6 



2.9 



Grams. 



Grams. 

 32.7 



Potato 



Crackers 



Fruit 



101.6 



283.2 



82.5 



4.9 

 3.2 



1.8 



















2, 876. 

 64.0 



1,857.2 



291.1 

 37.8 

 253.3 



217.8 

 7.3 



210.5 



467.3 



15.3 



452.0 



42.6 



Feces 



3.6 







39.0 

















87.0 



96.6 



96.7 



91.5 











Experiment No. 537, subject P. K.: 



Grayfish (in form of fish loaf) 



1,621.0 

 507.0 

 529.0 

 890.0 



1,117.3 



382.8 



36.5 



752.9 



281.1 

 12.7 

 42.9 

 3.6 



185.0 

 0.5 



70.9 



4.4 





37.6 



Potato 



105.9 

 374.5 

 126.4 



5.1 



Crackers 



4.2 



Fruit .' 



2.7 



Sugar 



















Total food consumed 



3, 547. 

 39.0 



2, 289. 5 



340.3 



17.7 



322.6 



260.8 



8.5 



252.3 



606.8 



8.1 



598.7 



49.6 



Feces 



4.7 



Amount utilized 





44.9 











Per cent utilized 







94.8 



96.7 



98.7 



90.5 













Experiment No. 538, subject C. J. W.: 



Grayfish (in form of fish loaf) 



1,331.0 



452.0 



202.0 



944.0 



12.0 



917.4 



341.3 



13.9 



798.6 



230.8 

 11.3 

 16.4 

 3.8 



151.9 

 0.4 

 27.1 



4.7 





30.9 



Potato 



94.5 

 143.0 

 134.1 



12.0 



4 5 



Crackers 



1.6 



Fruit 



2.8 

















Total food consumed 



2,941.0 

 65.0 



2,071.2 



262.3 

 27.7 

 234.6 



184.1 



13.9 



170.2 



383.6 



14.9 



368.7 



39.8 



Feces 



8.5 



Amount utilized 





31.3 











Per cent utilized 







89.4 



92.4 



96.1 



78.6 











Experiment No. 547, subject H. It. G.: 



Grayfish (in form of fish loaf) 



1, 142. 

 425.0 

 343.0 

 599.0 



762.2 



320.9 



23.7 



506.8 



219.7 



10.6 



27.8 



2.4 



132.2 



0.4 



46.0 



3.0 





27.9 



Potato 



88.8 



242.8 



85.0 



4.3 



Crackers 



2.7 



Fruit 



1 8 

















Total food consumed 



2,509.0 

 49.0 



1,613.6 



260.5 



26.7 



233.8 



181.6 



7.6 



174.0 



416. 6 



9.7 



406.9 



36.7 



Feces..- 



5.0 



Amount. iit.ili7 r firi 





31.7 











Per cent utilized 







89.8 



95.8 



97.7 



86 4 













i Jour. Biol. Chem., 16 (1913), No. 3, pp. 3S9-393. 



