256 



PISCES 



is very short, but receives the secretions from well-developed liver 

 and pancreas. 



In the Teleosteii, the teeth are premaxillary, vomerine, superior 

 pharyngeal, inferior pharyngeal, and mandibular. There are no 

 salivary glands, no spiracles and no posterior nares. The pharynx 

 is equipped with a fringe of gill rakers (strainers). The small non- 

 muscular tongue is supported by the ventral part of the hyoid arch. 



||gg||I^-- Top-pL 



Co/, epi , 



'^^T^.. Oobl. ce/f 



3as. mem. 



Fig. 139. A highly magnified view of a portion of the intestinal epithelium of the 

 sea bass, showing several columnar cells and a large goblet cell. The striated 'top- 

 plate' is evident, interrupted at the mouth of the goblet cell. Bas.mem., basement 

 membrane; CoLepi., columnar epithelium; Gobl.cell, goblet cell; Top-pl., top-plate. 

 (Courtesy of I. H. Blake, 7- Morph., vol. 50, Sept. 1930.) 



The gullet is broad and short, and the stomachy curved, is divided 

 into cardiac and pyloric regions with pyloric <r^f^^ ranging from six 

 in the perch to one hundred and twenty in the cod, and secreting 

 pancreatic enzymes. The pancreas is absent, but in a few teleosts, 

 pancreatic tissue is combined with the liver. In the goosefish, 

 and many other teleosts there are isolated Islands of Langerhans 

 in the mesentery that furnish the requisite " insulin." The Toronto 

 investigators have extracted it from fishes, and treated diabetes 

 successfully. 



