THE STRUCTURE OF IVORY 



I. TRANSVERSE SECTION OF ELEPHANT TUSK, ENLARGED 30 TIMES, SHOWING THE OUTER- 

 MOST STRUCTURE OR GROWTH RING IN WHICH THE BONE CANALS ARE DISTINCT, THESE 

 LATTER APPEARING AS SMALL DARK KNOTS ON THE RADIATING LINES. AT THIS ENLARGE- 

 MENT THE STRUCTURE NODES WHICH PRODUCE THE CLOTH OR LATHE-TURNED PATTERN 

 ARE TOO FAR APART TO COME INTO ALIGNMENT. 



II. ' NATURALLY WEATHERED TRANSVERSE FRACTURE OF A FLORIDA MASTODON TUSK. 

 ENLARGED ABOUT 12 TIMES TO SHOW HOW DISTINCTLY THE PATTERN DISCERNIBLE IN THE 

 TRANSVERSE SECTION IS PRESENT IN THE FOSSIL FORMS, AND EVEN CONDITIONS EROSION 

 OR WEARING OF THE TUSK FRAGMENTS. BUT THE CLOTH PATTERN IS ALSO QUITE PLAIN 

 ON THE FRESHLY BROKEN SURFACES. 



III. SECTION OF TUSK SHOWING FORM AND EXTENT OF INTERIOR HOLLOW PART. 



COURTESY OF PROF. G. R. WIELAND 



