150 H. J. HoHLiNG, H. Themann, J. Vahl 



In Fig. 3 the x-ray patterns of sound and diseased human tendon are represented 

 diagrammatically with the effect of increasing disease shown from left to right in the 

 figure. In the upper row wide angle patterns are seen in the lower row low-angle 

 patterns. Above all there is a loss of the 7.1 A- and 2.9 A-reflexions together with a 

 loss of the reflexions of the 640 A period. This loss indicates changes in the poly- 

 peptide chain. Such changes in the wide angle range have also been observed by us in 

 carious dentine. 



3 



Fig 4 Infrared diagrams of sound dentine collagen (Nr. 2). Carious dentine collagen (weakening of the inten- 

 sity of the ■> 9 A- and 7.1 A x-ray reflexions) (Nr. 1) and diseased human tendon (loss of the 2.9 A- and 

 7 1 A x-ray reflexions) (Nr. 3). In the case of carious dentine, diagram Nr. 1 (with collagen not so much de- 

 composed), there is a beginning of a peak, and in the case of diseased tendon, diagram 3 (with more decom- 

 posed collagen), a full peak in the range of 5.8 ,,. We conclude that it indicates a C = valence oscillation 

 resulting from broken peptide bonds in the polypeptide chains 



In the infrared diagrams (Fig. 4) of samples of carious dentine and diseased 

 tendon, showing decrease or loss of the 7.1 A- and 2.9 A-reflexion, we found the 

 same new peak near 1730 cm-'. It lies in the range of a C = valence oscillation. 

 Since the 2.9 A- and 7.1 A-x-ray reflexions had disappeared in the case of these 

 samples we concluded that peptide-bonds were affected or broken. This attack seems 

 to occur when the collagen fibers are split longitudinally to a sufficient degree. 



Summary 



In the case of collagen mineralization by apatite in dentine, cemcntum, bone and 

 tissues with myositis ossificans we observed on ultrathin sections: 1. light-looking, 

 elongated apatite crystallites (0 - 200 A) of the same length (^ 650 ± 50 A) ar- 

 ranged parallel and in rows. 2. strands of thinner (0 60-80 A), dark looking and 

 in general longer formations which were found also to be apatitic. 



From a variety of observations we concluded that the thin, dark looking apatitic 

 formations were formed earlier than the light-looking, thicker apatite crystallites; 

 that they were still in a more disordered stage of crystallinity and that the light- 

 looking apatite crystallites gradually developed out of them by a change to a better 

 state of atom arrangement in the crystal lattice. 



In carious dentine the thin, dark looking apatitic formations which cement the 

 colla-en subfibres were first decomposed. The collagen subfibers were then set free 



