Proceedings Forty-eighth Annual Meeting 87 



face to face with the fish food situation. Some commercial hatcheries are 

 boiling midlings and putting them in half and half to feed the fish. We have 

 always wondered how much of that grain was digested by the fish. The 

 paper goes right hand in hand with Dr. Embody's, but it shows what ter- 

 mendous difficulties one is under in keeping up with that side of the problem. 

 We cannot get at it the way we can with terrestrial animals. But if this 

 beginning made by Dr. Morgulis will lead to something, it means a good 

 deal, because we never know fully the value of different foods we are trying 

 until we know how much of those foods are assimilated by the fish we are 

 feeding. 



Dr. Geo. C. Embody, of Cornell University: I have been exceedingly 

 interested by this paper. It is possible to reduce some of Dr. Morgulis' 

 results to the same category as mine. For instance, what he calls the index 

 is exactly the same as what I call the reciprocal efficiency factor, that is, 

 one divided by the amount of food necessary to produce one pound of trout. 

 Now you will recall that in the case of millings, I secured a cost production of 

 one pound of trout at thirty-seven cents. The averages of his three exper- 

 iments with raw beef hearts makes a direct efficiency factor of 2.15, and if 

 hearts cost ten cents a pound, that means it costs only 21 cents a pound to 

 produce the trout, twenty-one cents compared to thirty-seven in the case 

 of liver — a distinct saving. 



The paper furnishes us data for solving some problems that we have 

 been wanting to solve for a long time. It shows a way for determining the 

 correct nutritive ratio between the amount of protein and carbo-hydrate, 

 a ratio which has been known for a number of years in the case of domestic 

 animals. The difficulty of finding it in the case of trout is due to the fact 

 that the nitrogen not only passes out by means of the feces, but through the 

 urine. There is no way of separating the urine from the feces, and conse- 

 quently no way of separating the nitrogen of the urine from the nitrogen 

 of the feces, which must be done before one can determine with any degree 

 of accuracy the correct nutritive ratio of these products with reference to 

 trout. I think this paper goes a long ways towards the solution of that one 

 problem, and will be exceedingly valuable for that as well as for many other 

 reasons. 



Dr. Henry B. Ward, of Illinois University: The paper is exceedingly 

 difficult to grasp thoroughly when one reads it. It must be more so than 

 when one sees it in print, because of the wealth of minute data of extreme 

 accuracy, which goes to safeguard the general results. But I am sure there 

 are some things which Dr. Morgulis would want to have indicated lest 

 improper conclusions be drawn from the statements in the paper. 



Now, as we know from feeding experiments with other animals, each 

 kind of food must be tested by itself, and to determine that these foods, 

 when cooked with the liver or beef hearts, are not as efficient as the 

 same food uncooked, does not prove that the same holds true of all kinds of 

 food uncooked. 



