1110 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



since with animals by other workers. While it would appear in some 

 respects to be the better method, there are reasons why it is not so 

 advantageous as the other, mainly because it is not capable of showing 

 such small differences, it is not free from nervous influences and personal 

 idiosyncrasies, and, lastly, it is less convenient. The method with arti- 

 ficial gastric juice, on the other hand, admits of the conditions being 

 the same in each case ; and, since the digestion of a food is by itself 

 simi)ly a chemical process, it would seem better in a determination of 

 digestibility that the i)rocess be shorn of all those conditions, natural 

 or otherwise, which tend to interfere with the purely chemical action 

 of the digestive juice. 



Few experiments appear to have been made on the digestibility of 

 fish; this is the more strange when we consider what an important 

 item of food fish constitutes, ])articularly along our seaboard. Yet the 

 idea is prevalent, based apparently on general grounds, that fish flesh 

 is not easily digestible. Thus IVIaly' mentions that " fish flesh is 

 diflicult of digestion, although the reason is not known." Still, as 

 Voit^ remarks, '"nothing certain is known regarding the digestibility 

 of different kinds of flesh, although much is said concerning it. 

 Probably digestibility is in part dependent upon the nature of the fat 

 present and the manner of its distribution 5 thus the presence of a 

 difficultly fusible fat with considerable stearin would tend to hinder 

 digestibility (as in mutton) ; the same thing probal)ly occurs when the 

 contents of the sarcolemma are permeated with much fat (as in the 

 lobster and eel)." This statement at once suggests the probability of 

 great variation in the digestibility of the flesh of any one species, 

 dependent on a large number of conditions, which, in the case of fish 

 particularly, are somewhat difficult of control ; thus age, sex, food, 

 period of spawning, length of time they have been preserved, are a few 

 of the many natural conditions which would tend to "modify the digesti- 

 bility of the flesh and render generalizations from even- a large number 

 of results somewhat uncertain. 



Still, as no systematic experiments appear ever to have been tried 

 with fish flesh, we have attempted to obtain some positive results 

 concerning the relative digestibility of the more common edible species, 

 as well as the general digestibility of fish as compared with beef, veal, 

 lamb, &c. 



THE METHODS EMPLOYED. 



The goMric juice. — For reasons already given, artificial digestion was 

 chosen as the best adapted for the x>urpose, and with this end in view 

 a gastric juice was needed which should be both constant in com- 

 position and activity during the length of time req.uired for trying 

 the experiments. A large quantity of so-called "pure pepsin'" was 



' Hermaun's Handhueh der Phi/fiioJogie, 5, 112. 



* Ibid., 6, 447. 



" Manufactureil by Heniy Thayer & Co. 



