BULLETIN OF THE UNITED STATES i^^ISH COMMISSION. 145 



Vol. VI, Wo. 10. tVashiisgtoii, ». C. Aiiff. 25, 1886. 



49.— ON THE FOO» AND DIGESTION OF GEKWIAN EISH.* 

 By Dr. P. FAl^CKITIUS. 



At the request of tbe Fishery Association of East and West Prussia 

 I couimeueed a series of anatomical and j)hysiological observations of 

 the alimentary canal and the digestion of our fish, which will not be 

 liuished for some time, but concerning which I am able to make a i)re- 

 liminary rei)ort. Any experiments in feeding made on the basis of 

 my results, will of course- have to be made only in suitably arranged 

 l)onds, as in the narrow tanks at my disposal the fish live under too un- 

 natural conditions to draw deiiuite conclusions as to the influence of 

 food on the increase of size and weight. 



The alimentary canal offish begins in the mouth, which is more or 

 less furnished with teeth, to which is joined a wide throat with folds 

 running lengthwise. The throat leads into a c^'lindrical tube, some- 

 times straight, and sometimes more or less twisted, which opens at the 

 anus. In the lampreys the entire alimentary canal is of an even, cylin- 

 drical form, and entirely straight 5 in some fish it is somewhat twisted, 

 but no distinction -can be recognized between the stomach and the in- 

 testinal canal 5 while in other fish the stomach may easily be recognized 

 as bag-like or at least as a considerably widened jiortion of that canal. 

 A microscoj)ic examination of the raucous membrane, which lines the 

 entire alimentarj' canal, shows that in a large group of fish, to which 

 among the rest the carp belong, the stomach is wanting, so that the 

 intestinal canal commences at the throat. It is a characteristic feature 

 of the stomach of fish, as well as of warm-blooded animals, that its mu- 

 cous membrane possesses pepsin glands. These glands secrete a fer- 

 ment (pepsin) which, together with a free acid produced by the glands 

 of the mucous membrane, digests albuminous matter, that is to say, 

 dissolves it and makes it fit to be received in the organism of fish. The 

 I)epsin of fish is distinguished from that of the mammals by the circum- 

 stance that even at a temperature far below 15° C. [SGOFahr.] it pos- 

 sesses an intensely digestive power, which is considerably increased by 

 raising the temperature to 40° [104° F.], while it is entirely destroyed 

 if the temperature is lowered to zero [32° F.]. In fish which i)ossess a 

 stomach the mucous membrane of the entire intestinal canal connected 

 with it shows no digestive faculties, but serves only to absorb the al- 

 buminous matter dissolved by the gastric juice. The gall secreted from 



* " Uehcr Kahnihrj vnd J'erdauuiujunnercr Finche." From Jlerichte dcs Fischerci-Vereins 

 der Proviuzen CM- und JVcfiijircnsscn ; 18S5-'8l), No. 2 ; Konigsberg, October, 1885. Trans- 

 lated from the German by Herman Jacobson. 

 Bull. U. S. F. C, 8G 10 



