Microns 



Figure 79. — Vesicular cells of connective tissue from the mantle of an adult C. virginica surrounding the blood sinus. 

 Blood cells crawl between the cells of connective tissue and penetrate into the sinus. Bouin 3, hematoxylin-eosin. 



opaque. These changes in appearance usually 

 coincide with seasonal cycles in the glycogen con- 

 tent of the connective tissue and with the progres- 

 sive stages of gonad development. 



The presence of glycogen can be easily demon- 

 strated by treating the tissue with Lugol solution 

 (1 percent iodine in 2 percent potassium iodide 

 in water). Specific reagents used for the identi- 

 fication of glycogen, such as Best's carmine and 

 Bensley's modification of Bauer-Feulgen reagent 

 (which stains glycogen granules red-\iolet), also 

 give good results. 



In the live oyster glycogen can be seen as small 

 colloidal granules which ooze from the tissue under 

 slight pressure. In preser\ed and stained 

 material it appears in the form of granules or 

 rods (fig. 82). The total amount of glycogen in 

 tlie connective tissue may be so great that the 

 blood vessels and nerves of the mantle are com- 

 pletely hidden under it and cannot be traced by 







30 



Microns 



Figure 80. — Vesicular cell of connective tissue 

 globules. Frozen section. Sudan IT. 



THE MANTLE 



with fat 



81 



