io8 PHYSIOLOGY OF THE INVERTEBRATA. 



liver of Arion riifns, as well as HcUx^ is a digestive gland 

 which is comparable to tlie pancreas of the Vcrtebrata. It 

 contains neither biliary pigments nor biliary acids. If one 

 considers that the A'ertebrate liver is not a digestive gland in 

 the proper sense of the word, since neither bile nor an infusion 

 of hepatic tissues contains digestive ferments, we may conclude 

 that the name of liver is in no way applicable to the diges- 

 tive gland of the Gasteropoda. 



It is stated by Barfurth that the liver of the Gasteropoda 

 performs the functions of a hepato-pancreas. It is certainly 

 pancreatic in fimction ; but there are no chemico-physio- 

 logical reasons for saying that it also possesses a liepatic 

 function. 



The salivary glands and "liver "of Patella vidgatct have 

 been investigated by the author,* The limpet (P, vidr/cdci), 

 with its conical shell adhering to the rocks of our coasts, is 

 well known to every sea-side wanderer. This member of the 

 Gasteropoda, has been the subject of many scientific memoirs 

 in ancient and modern times. Amongst naturalists, Aristotle 

 was the earliest who gave an account of some of the limpet's 

 habits, and Cuvier was the first to describe its anatomy. 

 Although this interesting little animal has attracted the 

 attention of many naturalists, it is only within the last 

 decade that the true functions of its internal organs have 

 been satisfactorily worked out. 



The " liver " of P<deUa ndcjcUa is a yellowish saccular gland, 

 and the greater bulk of this organ is encircled by the super- 

 ficial coil of the intestine. Its secretion acts upon starch- 

 paste converting the starch into glucose, as proved by 

 Fehling's solution. The secretion, as well as the organ itself 

 produces an emulsion with oils and fats, yielding subsequently 

 glycerol and fatty acids. The soluble ferment secreted by 

 the columnar cells of the epithelium of the gland is readily 

 extracted by either the Wittich-Kistiakowsky or Kravkoff 



* D)-. Griffitlis in Proncdhu/s of Jioyal Society of London, vol. 42, p. 393 ; 

 vol. 44, p. 328. 



