ALIiMENTAKV SYSTEM— -DIGESTIVE GLAND. 
■2 SO 
plentiful in many groups, Imt greatly reduced in number in the 
Limua'ida' and scarcely })resent in Snccined ; they probably represent 
a store of calcareous matter to be utilized in the growth of the shell 
or the formation of the epiphragm. 
The ferment is a rather thin dark yellowish fluid, decolorized and 
dissolved by Nitric Acid, and is probably a derivative of ha?matoidin. 
It is conveyed by the tiny lobular ducts which gradually unite together 
and linally enter the stomach anterior to the pyloric ciiecum, when 
present, but otherwise, usually behind the stomach and into the initial 
l)art of the intestine, by one or more, but usually by two chief 
ducts ; ill some cases, as in Ci/c/ostoiiKi, the ducts may bear isolated 
acini, wliich have been considered as pancreatic cocca, although such 
developments in the Cephaloiioda have been shown to correspond in 
function with the salivary glands of the higher Vertebrates. 
'I'he digestive gland functions chiefly as a pancreas, but there are 
reasons for regarding it as also possessing hepatic functions. The 
peptic ferment is stated to be identical with Krukenberg’s llelico- 
pepsin, while the diastatic ferment, which disappears during 
hibernation, is stated to be capable of dissolving raw starch, but has 
no action on cellulose. The fat emulsifying power also disapiiears 
in winter. 
In the Pelecypoda generally the dige.stive gland has been ascer- 
tained to contain Diastatic ferments, I’ancreatin, Peptones and 
doulitfully (ilycogen, while in (lastropoda tlie contents are similar 
with the addition of Sodium. Put the preci.se constitution of the 
(iastrojiod liver, as e.xemplifieil in /It'li.v ponmtht, is, according to 
Dr. Levy, by alcoholic extract, Enterochlorophyll, Lecithin, Oleic 
and fatty Acids, and as ash. Chlorine, Pho.siihoric and Suljdiuric 
acid. The a(pieous extract yielded Sugar, Glycogen, Sinistrin, 
Globulin coagulating at Gbc, Ilypoxanthin and other bases precipitable 
by iihototungstic acid, and as a.sh. Potassium, Sodium, Calcium, 
Magnesium, ^langanese, Cblorine, Phosphoric and Sulphuric acids, 
with traces of iron. In winter .silica was also found as an ash 
constituent. The ethereal extract yielded onl)^ a trace of fat. 
Glycogen (C,iIIioOs) or, as it is sometimes called, Liver-sugar, 
is a white amorphous amyloid substance, insoluble in alcohol or ether, 
and when dissolved in water exhibits a strong dextro-rotatory in- 
tluenee on polarized light, and is distinguished by its power to change 
to sugar or glucose in the presence of animal ferments. It is found 
