34 



lii'lwcrii tlir cai't ilasAvs al((i\c llic ladiila and radulai' ivtrarlurs fDiiiis with the 

 IdWiT nuisclc ail i)hh(|uel)' cniiical lulic which contains the radular sac and over 

 whose apex the ra(hila,i' inc^inbraiir is retlected. 



The radular retractors arise from I he dorsal end of tlic radular cartilages 

 and extending forward parallel Id lln' I'adula are inserted near the venlral mds 

 of the cartilages upon the subiiulular nienibi'ane. 



Tile protractors of the radula arise from the lower edge of the upper jaw 

 and passing forward and inward are inserted upon the reflected distal end of the 

 suhradular uieiubrane. A small portion of the protim-tor is inserted upon the 

 toothless i»ortion of the same meniluanc which, it will be i-eniembered , covers 

 the sides and lop of the odontophore. Tlie alternate contraction of the retractors 

 and protractoi's draws the i-adula back and forth over the ventral end of the 

 radular cartilages. The teeth art only during retraction hence the retractors are 

 much more poweiful than the protractors. 



The mouth, the oesophagus, the radular sac, the median and the paired 

 salivary glands and probabl>' the stomach also arise from the stomadaeum. 



The salivar)- glands are relatively simple compound-tubular glands. The lumina 

 are large and are surrounded by palisadal cells whose large nuclei are situated 

 next the supporting membrane and whose distal halves are tilled by large secre- 

 tion vacuoles. The secretion in the lumina is usually precipitated by fixatives. An 

 incomplete series of tests showed that aipieons and glycerine extracts of the median 

 gland aie not oleolN'tie or amylolytic , and that they are probably proteol\'tic. 

 FAt.LoisE finds this to be the case. The glands also secrete mucin. 



Henze confirms the observations of Lo Bianco, Krause, and Livon & Bkiot, 

 that the secretion of the posterior salivary glands of various cephalopods injected 

 into the circulation of crustaceans, even in small quantities, is quickly fatal. 

 Henze finds that th(^ poison is an organic base (alkaloid) similar to the poison 

 tif bees and of the skin of salamanders. The gland contains also two nitrogenous 

 substances ; one of these, taurin, is very abundant in the muscles of cephalopods, 

 and since von FUrtu has found very little niti'ogen in the secretion of the 

 ne])hridium, Henze suggests that the gland is, at least in part, excretory. 



The paii-ed or buccal salivary- glands are partially- imbedded in the muscles 

 upon I he dorsal surface of the pharynx between the i'adula and the oesophagus. 

 The duct of each gland passes througli the palatine lol)e and opens into the 

 mouth oil the inner side of the lobe near its ventral end. The median salivary 

 gland is a small oval body imbedded in the ventral end of the liver. It lies in 

 a small venous sinus situated beneath the oesophagus and between the diverging 

 visceral and pallial nerves. Its duct accompanies the oesophagus through the 



