STOMACH AND PYLORIC APPENDAGES. ' Hu 



Tlirough the pyloric orifice, partially digested food reaches the com- 

 mencement of the small intestines, and as a rule we observe that the distance 

 from the pylorus to the vent is shorter in fishes than in most of the higher 

 vertebraita. But of course the length of the intestinal tract differs in various 

 classes, while its lining membrane is by no means of the same description in 

 all. In the salmon or herring we find the length of the intestines shorter 

 than that of the body, but in the former the intestinal lining membrane is 

 raised into transverse folds, thus increasing the extent of their secreting and 

 absorbing surface, which is also further augmented by the secretions of 

 numerous coecal appendages. In the herring, again, the coeoal appendages 

 are numerous. In other forms we find the intestines themselves convoluted, 

 thus increasing their length, and this is well seen among the carps. In the 

 shad Cuvier observed that valvulse conniventes existed, in the intestines, 

 while in the salmon the folds of the internal lining of the intestines increase 

 in size, decrease in number, and become less oblique as they approach the 

 rectum, or the commencement of the large intestine' is marked by a large 

 circular valve, which is succeeded by several others which are completely or 

 incompletely transverse. This large intestine may be straight, as seen 

 in the sturgeon orchimsera, &c., where the transverse folds may become 

 continuous, and there is formed an uninterrupted spiral valve, also present 

 in the sharks, the rays, and their allies, but which may be modified into . 

 transverse coils. 



It is thus that in fishes economy of space is effected by an increase of the 

 secreting and absorbing surface of the vasculo-mucous membrane lining the 

 intestinal tract, whether such be merely raised into puckers, or these puckers 

 be continued into transverse folds, or even forming a circular uninterrupted 

 spiral valve or coil to the large intestine. 



. An examination into the ccecal appendages, also termed pyloric coeca, 

 and pyloric appendages — what forms possess and whtlt are deficient in them 

 — under what circumstances they vary — and, lastly, what are their functions, 

 show them to be questions respecting which much still remains to be 

 ascertained. In different fishes they may be useful for different purposes — 

 either as an absorbing or secreting surface, or both. Thus as observed by 

 Krukenberg, in the perch they are lined by simply-mucous glands, whereas in 

 the herring they represent the pancreas, and contain a " tryptic " ferment. In 

 some species these appendages are a modified pancreas, in addition to the very 

 rudimentary form of this organ which has been detected as a minute glandular 

 body, terminating in a duct, which opens by from one to three orifices into the 

 intestines, close to the bile duct, but occasionally so closely attached to the 

 latter as to be easily overlooked. The latter is seen both in fishes which possess 

 pyloric appendages, as perch, cod^ salmon, sturgeon ; and in such as are 

 deficient in them, as brama, gar-pike, and pike, while the sharks and rays are 



