PHYSIOLOGY OF THE INVERTEBRATA. 



73' 



odontophore. It leads into a long oesophagus, which is 

 narrower in the DihrancMata than in the Tefrabranchiata, and 

 then dilates into the muscular stomach. The pyloric portion 

 of the stomach communicates with a glandular sac — the 

 pyloric ceecum. The intestine is bent somewhat upon itself, 

 passing towards the neural 

 (ventral) end of the body 

 and terminating in a median ■ 

 anus. One or two pairs of 

 salivary glands are present 

 in the Dibranchiata, which 

 pour the secretion into the 

 buccal cavity or the anterior 

 portion of the oesophagus. 

 The so-called liver is a well- 

 developed bilobed organ 

 provided with two ducts, ■, 

 which in theDecapoda receive 

 the ducts of a large number 

 of caecal appendages. It 

 has been considered that 

 these appendages are the 

 rudiments of a pancreas; 

 but there is no doubt that 

 the so-called liver per se is 

 essentially pancreatic in 

 function. This organ does 

 not give rise to any of the 

 biliary acids (glycocholic 

 and taurocholic acids) nor 

 glycogen. The colouring 



matters which the so-called liver contains, do not answer 

 chemically to bilirubin and biliverdin. But its secretion con- 

 tains leucin, tyrosin, and a ferment (or ferments) which con- 

 verts starch into glucose. 



The ink-bag is a tough, fibrous, glandular sac. It is usually 



Fig. 20.- 



-Alimentary Canal of 

 Sepia. 



a = buccal mass, i = salivary glands. 

 c = oesophagus, d = so-called liver. 



e — pancreatic follicles (so-called). 



/ = stomach, g = pyloric caecum. 



h — ink-bag. i = intestine, k = anus. 



