31 



fectly transparent, and seen singly, colourless ; in mass 

 the substance is very slightly yellowish. The length, 

 when taken from full-grown specimens, varies from 20 to 

 26 mm. The diameter decreases from above downwards, 

 and may be taken as about 1 mm. The proximal 

 extremity always projects into the cavity of the stomach, 

 and is opaque and slightly frayed ; the distal extremity 

 does not fill the lumen of the ventral portion of the sheath, 

 but remains adherent to one portion of the wall. It is 

 firm, somewhat elastic, but breaks easily. 



Barrois,* in an exhaustive memoir on the Morpho- 

 logy and Physiology of the Lamellibranch Style, gives an 

 account of the chemical composition and reactions of the 

 substance of which it is composed, which may be briefly 

 summarized here. Barrois made his analysis and experi- 

 ments on the crystalline styles of Cardiuni edule. The 

 style has an average weight of 0'026 grm. It is a colloidal 

 substance. A number placed together coalesce to form a 

 transparent jelly, which takes the form of the vessel in 

 which it is contained. Dried at a temperature of 120°, the 

 mass contracts considerably in volume, but still remains 

 perfectly transparent and somewhat moist. On ignition a 

 small amount of inorganic ash remains. The fresh style 

 is rapidly soluble in concentrated hydrochloric acid to a 

 bluish solution ; it is slowly soluble in water, forming a 

 slightly opaque and viscous solution. Millon's reagent 

 gives a red colouration in the warm. Treated with copper 

 sulphate solution and caustic potash, a fine blue colouration 

 is obtained. These reactions indicate the presence of an 

 albuminoid substance. 



When the solid styles are boiled with dilute sulphuric 

 acid, and the acid solution neutralized and precipitated 

 with alcohol, a solution in the latter solvent is obtained. 



* Revue Biologique du Nord de la France. T. I. and II., 1889—90, 



