12 Moll. 
MOLLUSCA, 
Physiological experiments on the muscles of the Bivalves, the current 
of electricity being the most powerful agent on them, by Constance, 
Bull. Soc. Brest, 1879; abstracts in Kev. Sci. Nat. ii. p. 117, and J. R. 
Micr. Soc. hi. p. 7G5. 
Chemical notes on the muscular substance of several Mollusca^ 
“ Taurine ” found in the adductor muscles of various Bivalves and in the 
muscles of some Gastropods ; probably “ tyrosine ” in the muscles of 
Eledone. C. P. Krukenberg, Vergl. physiol. Studien, ii. pp. 8, 9, 13, 
30-35. 
3 . Formation of the Shell. 
Longe & Mer have examined the formation of the shell in land snails, 
especially Helix. They have found near the anterior margin of the mantle 
a peculiar modification of its structure, which they name “ appareil cuto- 
gene,” consisting, first, of a furrow or groove parallel to the margin, and, 
secondly, behind it, of a layer of bottle-shaped cells which appears upon 
an antero-posterior section, like an epithelial wedge buried in the sub- 
stance of the mantle (epithelial organ). The glandular coeca at the 
bottom of the pallial groove secrete mucus, perhaps conchioline ; the 
bottle-shaped cells secrete granules, soluble in potash ; both assist in 
forming the cuticle of the shell. This apparatus exists in the embryo 
when still enclosed in the ovular envelopes, and ' continues during the 
whole of growth of the snail. In the adult, the bottle-shaped cells and 
glandular coeca of the furrow are gradually atrophied, but the furrow 
remains, thus explaining why the aperture in most adult Helix is first 
slightly narrowed and then turned outwards. The deeper calcareous layers 
of the shell are secreted, as is well known, by the whole surface of the 
mantle. When a part of the shell has been injured and is re-formed, 
calcareous rods first appear, which gradually become enlarged at the 
extremities and acquire the form of small sacs, being further converted 
into spheres, the dimensions of which are increased by concentric deposits 
with radiating striae ; these finally come in contact with each other and 
form a continuous stratum. C. R. vol. xc. pp. 430-432 ; Ann. N. H. (5) 
y. pp. 430-432. 
4 . Digestion. 
Chemical observations on the hepatic fluid in various Mollusca by 
C. F. Krukenberg; Chiton agrees in this respect with the other Mollusca 
and differs from the Vermes in the want of “tryptical enzyme”; in 
Tethys, .the hepatic fluid has no peptic power : Vergl. physiol. Studien, i. 
pp. 68-60. Spectroscopical note on the pigments of the liver in various 
Mollusca ; pp. 182, 188 & 189, table. “ Taurine ” and small quantities of 
urea found in the liver of some Mollusca ; pp. 30-33. A large quantity 
of fat exists in the liver of many Mollusca^ and fat is scarce only in 
Myiilus edulis \ p. 41. 
Three different sorts of cells found in the liver of A now, Helix^ and 
Limax — fermenting cells, liver cells, and others filled with colourless 
granules of carbonate of lime ; this third sort of cells is wanted in 
