36 WILLIAMS: GLYCOGENIC FUNCTION IN THE MOLLUSCA. 



exist in the case of the MoUusca ? Their food is essentially, in 

 the majority of cases, a vegetable one, and forming the chief 

 chemical constituents of plants are carbohydrates and proteids. 

 The carbohydrates are starch, inulin, dextrin, and sugars includ- 

 ing glucose, cane sugar, and various others. Proteids are there 

 as protoplasm, aleurone grains, crystalloids, gliadin, vegetable 

 fibrin, and a native albumen which is soluble in water and 

 coagulable by heat and, in many respects, identical with animal 

 albumen. Free sulphuric acid has been demonstrated in the • 

 secretion of the salivary glands of MoUusca by Panceri, Troschel 

 and Quoy* and this according to E. Bourquelot' changes 

 starch into sugar in the Cephalopoda, and the same amylolytic 

 function has been shown by E. Bonardi*^ to be possessed by 

 the salivary secretion of the Pulmogastropoda ; L. Fredericq^ 

 has demonstrated a ferment in the enteric canal of Arion ater 

 which changes starch into sugar ; E. Bourquelot^ has found 

 that the secretion of the pancreas of Cephalopods contains a 

 diastatic ferment which is identical, in its action, with the 

 amylopsin of the Vertebrates, and that there is also present 

 trypsin which changes proteids into peptones after the orthodox 

 method described as existing in the Mammalia ; while A. B. 

 Griffiths ° has also proved a diastatic ferment to be present in 



4. " Gli organi e la secrezione dell' acido sulfurico nei Gasteropodi con 

 una appendica relativa ad altra glandole dei medesimi. " Ann. !:ci. Nat. 

 vol. X pp. 89-94 ; also Am. J. Sc. (2). xix. pp. 420-422. 



5. Arch. Z. exper : x. pp. 384-421. 



6 " Intorno all azione saccarificante della saliva ed alia glicogenesi 

 epatica in alcuni Molluschi terrestri." Boll, scient. v. pp. 83-86. 



7. Arch. Z. exper : vii. pp. 397-399. 



8. " Recherches relatives a Taction des sues digestifs des Cephalopodes 

 sur les matieres amylacees " Compt. Rend, xciii. pp. 978-980 ; Abstr. J. R. 

 Micr. Soc. (2). ii. p. 30. Also " Recherches sur les phenomenes de la 

 digestion chey les Mollusques Cephalopodes." Arch. Z. exper (2). iii. 

 pp. 1-74. 



9. " Chemico-Physiological Investigations on the Cephalopod Liver 

 and its Identity as a True Pancreas" P. R. S. Edinb. xiii. pp. 120-122; 

 Chem. News, xlviii. p. 37., li. p. 241 ; J. Chem. Soc. xlvi. p. 94., 1884; 

 Abstr. J. R. Micr. Soc. (2) v. p, 622. 



J.C., vi., Jan., 18S9. 



