DEVELOPMENT OF THE ENAMEL 



141 



In many parts of the calcareous deposit in the albumin 

 experiments, the globules are seen to have coalesced ; they 

 are often arranged in rows around a central extension filled 

 with minute spherites, and in other places where in contact, 

 have become fused into larger bodies, hour-glass-shaped and 

 double spherites being very frequent. 



The larger ones show a tendency to disintegrate, the 

 central part breaking down into smaller elements (fig. 80,/). 

 In many of the larger radial spherites, beside the delicate 



a e f. 



FIG. 80. Calcospherites. a. Concentric form (formed in albumin); 

 b. radial form (formed in albumin); c. radial spherite from marsupial 

 forming enamel ; /. a similar one disintegrating ; d. oval spherite from 

 human developing enamel ; e. granular spherite from human enamel. 



radial striae, wider spaces are seen extending from the 

 centre to the circumference, of an irregular shape, and 

 evidently indicating a splitting or dividing of the spherite 

 into sections. This is frequently seen in the disintegrating 

 globules in enamel, presently to be referred to. 



The occurrence of calcospherites in the living animal may 

 be well studied in the carapace of the prawn und in the claw 

 of the crab, as was pointed out by Rainey. A fragment of 

 the transparent carapace of the prawn, mounted in glycerine 

 without any previous preparation, shows the spherites very 

 beautifully in all stages of coalescence and disintegration 

 (fig. 81), and in the crab their incorporation in the hard 



