DEVELOPMENT OF THE ENAMEL 159 



them. Some of the large calcospherites are seen to be 

 splitting in a radial manner into three or four segments, and 

 are surrounded by small granules. These large calcospherites 

 vary greatly in size, but they also show the radial type of 

 formation, no concentric spherites being visible. 1 



Fig. 91 is particularly instructive, for it shows that small 

 uniform calcified bodies are building up the enamel prisms, 

 while large calcospherites are lying between the laminae and 

 showing indications of breaking down into smaller particles. 



FIG. 90. Fragment of enamel from developing tooth of Macropus teased 

 out in glycerine, showing laminae and spherites. ( x 140.) 



These appearances would seem to indicate that the enamel 

 prisms are calcified independently of the interprismatic 

 substance, the prisms being formed by the fusion of these 

 small calcospherites into the regular blocks of calcified sub- 

 stance seen in mature enamel, while the larger bodies by 

 their fusion and disintegration form the cementing or 

 interprismatic substance. As will be shown later, however, 

 and distinctly seen in fig. 94, these larger bodies are not 

 always broken up, but become fused with one another. 



1 The calcospherites in these figures may be compared with the artifi- 

 cially formed spherites shown in fig. 80. 



