. The physiology of the Invertebrata. cum. The intestine is bent somewhat upon itself,passing towards the neural(ventral) end of the bodyand terminating in a median ?anus. One or two pairs ofsalivary glands are presentin the Dibranchiata, whichpour the secretion into thebuccal cavity or the anteriorportion of the so-called liver is a well-developed bilobed organprovided with two ducts, ?,which in theDecapoda receivethe ducts of a large numberof caecal appendages. Ithas been considered thatthese appendages are therudiments of a pancreas;but there is no doubt thatthe so-called liv
. The physiology of the Invertebrata. cum. The intestine is bent somewhat upon itself,passing towards the neural(ventral) end of the bodyand terminating in a median ?anus. One or two pairs ofsalivary glands are presentin the Dibranchiata, whichpour the secretion into thebuccal cavity or the anteriorportion of the so-called liver is a well-developed bilobed organprovided with two ducts, ?,which in theDecapoda receivethe ducts of a large numberof caecal appendages. Ithas been considered thatthese appendages are therudiments of a pancreas;but there is no doubt thatthe so-called liver per se isessentially pancreatic infunction. This organ doesnot give rise to any of thebiliary acids (glycocholicand taurocholic acids) norglycogen. The colouring matters which the so-called liver contains, do not answerchemically 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. -Alimentary Canal ofSepia. a = buccal mass, i = salivary = oesophagus, d = so-called liver. e — pancreatic follicles (so-called). / = stomach, g = pyloric caecum. h — ink-bag. i = intestine, k = anus. 74 PHYSIOLOGY OF THE INVERTEBRATA., of an oblong pyriform shape, and secretes a brown or blackfluid, the colour of which is very durable. The Tetrabranchiata are represented by the only existinggenus, Nautilus, which is provided with an external chamberedsiphunculated shell. Like that of the Sepia, the mouth of the Nautilus is armedwith powerful jaws (Fig. 21). It leads into an oesophaguswhich dilates into a wide crop. The crop passes into the
Size: 1307px × 1912px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectinverte, bookyear1892
