MOLLUSCA. 



259 



Chinese as charms. These figures generally represent Buddha in the 

 sitting position, in which that image is most frequently portrayed." 



The microscope discloses the different structure of pearls : those 

 having a prismatic cellular structure, have a brown horny nucleus, sur- 

 rounded by small imperfectly- formed prismatic cells ; then there is a 

 ring of horny matter, followed by other prisms, and so on, as repre- 

 sented in fig. 112, which are transverse sections of pearls from oysters, 

 showing successive rings of growth, or deposits. 



In a horizontal section (fig. 113) of another pearl, the prismatic 

 structure and the transverse grooves of the prisms are very well 



fig. 113. 



1. A transverse section of a small pearl from a species of Mytilus. 2. A horizontal 

 section of a Pearl magnified 250 diameters, showing its prismatic structure, and 

 the transverse striae of the prisms. 



shown. The prisms are smallest in the centre, and nearly filled with 

 dark matter, as are also some nearer the edge. In a segment of a 

 transverse section of a small purple pearl from a species of Mytilus, all 

 trace of prismatic structure has gone, and only a series of fine curved 

 or radiating lines are seen. It consists of a beautiful purple-coloured 

 series of concentric laminse (fig. 113). Many of this kind of pearls 

 have a series of concentric zones, and some are of a yellow tint. The 

 most beautiful sections for microscopic examination are obtained from 

 Scotch Pearls. 



