434 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



Along with these a parallel series of analyses of meats, dairj^ i)rod 

 ucts, and other food materials, animal and vegetable, have been under 

 taken, at the instance of the United States National Museum, to furnish 

 data for illustrating and exi^laining its food -collection. These analyses, 

 though not specifically a part of the investigation herewith reported, 

 form a most important supplement to it, because of the great desira- 

 bility of data for comparisons of fish with other foods. The number of 

 analyses of the latter kind already made is 90. These, with the 182 of 

 food-fishes and invertebrates, give a general idea of the amounts of 

 nutritive substances in our more common foods. Of course, an at all 

 complete and satisfactory knowledge of the subject will require the 

 prosecution in much more detail of the work of which these analyses 

 represent only the beginning. 



II. Experiments upon the digestibility of the flesh of fish. 



The importance of studying the digestibility of the flesh of fish led 

 me to improve the occasion of a stay in Munich, Germany, to conduct 

 a series of experiments upon this subject. In this I was very mate- 

 rially aided by Professor von Voit, who courteously placed the needed 

 room and apijliances in the physiological laboratory of the University 

 at my disposal, and rendered material assistance by his counsel. 



The general outcome of the experiments may be expressed in a few 

 words. The proportions of the nutrients digested were tested in a 

 series of experiments with a healthy man and with a dog. The man 

 digested some 98 per cent, of the protein of the fish and nearly the 

 same proportion j&"om meat (lean beef). That is to say, the digestion 

 of the protein of both meat and fish was nearly complete. Essentially 

 the same results were obtained for the other nutritive ingredients. 

 The experiments with the dog gave practically like results with both 

 kinds of food. 



Eegarding the ease and rapidity of the digestion of fish, the experi- 

 mental evidence is as yet insuflScient for exact conclusions. The in- 

 vestigations thus far made upon the constitution of the ingredients of 

 the flesh, as well as those upon artificial digestion, indicate no great 

 difference between the fish and the leaner meats, as lean beef, and imply 

 that both would be very readily digested. In brief, the experimental 

 facts at hand do not indicate any decided difference in digestibility be- 

 tween fish and the leaner meats. Both belong to the more readily and 

 completely digestible foods. 



III. Studies of the chemical constitution of the proximate ingredients of 



the flesh of fish. 



It was my fortune to spend some months in Heidelberg, where Pro-' 

 fessor Kiihne, of the University, kindly offered me the facilities of tlie 

 physiological laboratory under his charge, and added his own valaabl^i 

 assistance in the prosecution of an inquiry into the constitution oj 



