The Cambridge natural history . Fig. 142. —Portion of tlic radula of Octopus ietra-cirHuis D. Ch., Naples, x 20. SALIVARV GLANDS 237 each of which has a small accessory plate at the base. The twolaterals and the central tooth are small, very similar to oneanother, nnicnspiel on a square l)ase. Salivary (/lands are found in most Glossophora. They occur inone or two pairs on each side of the pharynx and oesophagus, theduet usually leading Iorwards and opening into the anterior partof the pharynx (see Figs. 143, 144). They are exceptionallylarge in the carnivorous (Tasteropoda. In certain genera,
The Cambridge natural history . Fig. 142. —Portion of tlic radula of Octopus ietra-cirHuis D. Ch., Naples, x 20. SALIVARV GLANDS 237 each of which has a small accessory plate at the base. The twolaterals and the central tooth are small, very similar to oneanother, nnicnspiel on a square l)ase. Salivary (/lands are found in most Glossophora. They occur inone or two pairs on each side of the pharynx and oesophagus, theduet usually leading Iorwards and opening into the anterior partof the pharynx (see Figs. 143, 144). They are exceptionallylarge in the carnivorous (Tasteropoda. In certain genera, , Dulium, Cassis, Flc/urohranclms, the secretions of theseglands are found to contain a considerable proportion (sometimesas much as 425 per cent) of free sulphuric acid. This fact was. Fig, —Alimentiiry canal of Helix aspersa L.: «, anus; ,h.(l, riglit and leftbiliary ducts ; , buccal mass ; c, crop ; , lierniaplirodite gland ; i, intestine ;{.0, opening of same from stomach (pyloric orifice); /, I, right and left lobes ofliver ; m, mouth ; oc, oesophagus ; r, rectum ; , salivary duct ; , salivarygland ; st, stomacli ; t, left tentacle. (After Howes and Marshall, slightlymodified.) lirst noticed l)y Troschel, who, while handling a Dulinm galea atMessina, saw the creature spit a jet of saliva upon a marble slab,which immediately produced a brisk effervescence. A numberof the genera thus provided Ijore through the shells of other]\Iollusca and of Echinoderms, to prey upon their soft tissues, andit is possible that the acid assists in the piercing of tlie shell byconverting tlie hard carbonate of lime into sulphate of lime,wdiich can easily be removed by the action of the radula.^ Inthe majority of the Ceplialopoda there are two pairs of saliv
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
