rS^' 







Microns 



60 



Figure 97. — Calcite crystals deposited on a piece of conchiolin. Photomicrograph taken 38 hours after the secretion of 



conchiolin has started. 



contribute to this process by transferring phos- 

 phate to some substrate and removing the phos- 

 phate ions. This tentative e.xphination suggests 

 a number of biochemical studies that should he 

 made to obtain a better understanding of the 

 process of calcification. 



An important factor in the process of shell 

 calcification is the enzyme phospiiatase, which is 

 generally present in the ossifyiiig cartilages of 

 young animals and in other tissues and organs in 



which calcium is deposited. The action of tlie 

 enzyme consists of liydrolysis of he.xosemonoplios- 

 phoric ester and glycerophosphoric ester and 

 consequent liberation of inorganic phosphate. 

 Tlie role of phosphatase in tlie shell formation of 

 niollusks was established by Manigault (1939), 

 who found a direct correlation between ph,os- 

 phatase activity in the digestive diverticula, 

 numtle, and blood and precipitation of calcium in 

 the shell. He concluded tluit phosphatase is 



98 



FISH AND WILDLIFE SERVICE 



