134 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



taking the silver impregnation more deeply than the rest. 

 The upper part of the figure represents the structure of the 

 concretion within the concentric, deeply impregnated capsular 

 structure. 



The material of the concretion becomes very hard on 

 dehydration and embedding in paraffin, so that thin, micro- 

 tome sections cut in this way break up easily, and it is difficult 

 to make out their structure. It is apparent, however, that the 

 greater part of this laminar marginal part of the concretion 

 is a product of cellular proliferation. It is crowded with very 

 small, altered nuclei, which are embedded in a tissue which 

 shows no distinct cell boundaries. This is the structure of the 

 dark part in fig. 2, and directly above it, that is towards 

 the central part of the concretion, is an obscure layer of what 

 appear to have been vacuolated cells, elongated in a direction 

 which is radial to the concretion. External to the dark part, 

 the appearance of the tissues suggests that of a hypertrophied 

 fibrous connective tissue. 



The substance of the concretion internal to this dark 

 capsular margin consists of a semi-translucent cartilaginous 

 looking mass, apparently homogeneous to the naked eye. 

 Fig. 3 represents a small part of this- — a thin hand-cut section 

 stained with Mayer's haemalum and eosin, and it is now seen 

 that the substance is not homogeneous. It consists of a 

 ground-substance or matrix staining pink, with haemalum- 

 eosin, and in this are strips, or sections of sheets, of some other 

 substance which stains a faint blue with the haemalum. 

 These strips are not homogeneous, for there is a more deeply 

 staining band in the central part of each of them. In the 

 matrix there are numerous granules, and lighter staining parts 

 as well as sheaves of what appear to be crystals, prismatic in 

 form, and with the prisms arranged usually in radial groups. 



What all this structure at once suggests is, first of all, 

 an abundant proliferation of the connective tissue in the 



