Figure 99. — Photomicrograph of organic meshworlc of prismatic Layer of shell after decalcification in weak hydrochloric 

 acid. Note that the outlines of the capsules retain tlie shape of the mineral prisms. 



conchiolin of tlie shell indicate that carbon dio.xide 

 fixation also contributes to the syntheses of the 

 organic matrix of the shell. 



Calcium enters the mantle directly from sea 



water, as was demonstrated by Jodrey (1953) 

 usino; mantle-shell preparation and radioactive 

 Ca*^, and can he taken up through other parts of 

 the moUusk and transported to the mantle. The 



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