ALIMENTARY CANAL, ETC., OF AMIUKUS CATUS. 401 



tinction of these into parietal and chief cells, such as obtains in 

 higher vertebrates, is totally absent in fishes. Nussbaum 1 describes 

 two varieties of peptic cells in the pike ; one consisting of large 

 coarsely granuled cells situated anteriorly and followed by a zone of 

 second variety behind, which includes small finely granuled cells. 

 Such a distinction in these cells, both as regards structure, relative 

 position and size, it may be remembered also exists in the frog. 

 Langley and Sewall 2 find but one kind, of cells in the stomach of 

 Gasteropodus trispinatus. 



Cajetan 3 corroborates Nussbaum's description of the cells in the 

 pike, and also finds a similar distinction in the cells of Cobiiis 

 barbatula. 



In spite of these discoveries of Nussbaum and Cajetan, which 

 are of but doubtful value as regards a functional difference, Edinger's 

 statement, that chief and parietal cells, as such separately, are absent 

 in fishes, is still to a great extent true, and it may be regarded as 

 established that whatever may be the functions of these cells in 

 higher vertebrates, such functions are performed by one kind of cells 

 in fishes. In those fishes of which I have studied the stomach 

 glands for the sake of comparison with those of Amiurus. all, with 

 the exception of the sturgeon, showed not the slightest difference 

 from the description already given above. I can only compare these 

 glands to those of the oesophagus of the frog, as described by 

 Langley 4 . 



The pyloric mucous surface is like that of the cardia and ccecum 

 in the forms of its constituent cells. True glands are absent, what 

 is usually called such in fishes, being simply indippings or crypts of 

 the membrane, and clothed with long cylinder cells which are not 

 different from those of the general surface. They are found up to 

 the pyloric valve, where they pass gradually into the crypts of 

 the midgut. It may be mentioned that as the pylorus is approached, 

 the crypts into which the peptic glands open elongate, the glands 

 diminish in length, and finally vanish, leaving in their place a much 

 elongated crypt. 



The membiana propria of the peptic glands consists of fibres of 

 the mucosa closely applied in the form of a sheath, in which are 



1 Archiv fur Mikr. Anat. Bd. XXI. 2 Journal of Physiol. Vol. II. 



3 ZurLehre von der Anat. und Physiol, des Tract. Intest. der Fische., Bonn, 1883. 



4 The Histology and Physiology of the pepsin-forming glands. Phil. Trans. Vol. 172, Pt. III. 



