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to confirm the view as to its double nature, for one can see in the 

 plate of cartilage which covers its extremity, two distinct ossific centres, 

 one, which tips the more anterior and downwardly directed segment, 

 the other covering the more posterior segment (Fig. 2, C, T). In two 

 specimens in my possession both of the age of 18 these centres are 

 well seen and they are especially notable in those cases where the 

 5th lumbar vertebra is fusing with the sacrum (Fig, 2). 



If these observations on the 5th lumbar vertebra be kept in mind 

 in our examination of the sacrum, it will, I think be seen that they 

 will solve the manner of completion of ossification of that bone. 



The sacrum at 18 years of age shews all the centres which go to 

 complete the process of ossification, and we may examine it from the 

 front, the sides and the back. 



Fig. 2. The 5th Lumbar 

 vertebra and the Sacrum 

 from the front. On the left 

 side the fifth lumbar vertebra 

 is in process of fusion with 

 the first sacral vertebra. 

 T. Transverse process and 

 epiphysis of the fifth lumbar 

 vertebra. C. Costal process and 

 epiphysis of the fifth lumbar 

 vertebra. A. C. 1 Anterior 

 costal epiphysis of 1st sacral 

 vertebra. A. C. 2 Anterior 

 costal epiphysis of 2nd sacral 

 vertebra. A. C. 3 Costal epi- 

 physis of 3rd sacral vertebra. 

 A.C. 4 Costal epiphysis of 

 4th sacral vertebra. 



In Fig. 2, one sees from above downwards on the left side the 

 transverse process of the 1st sacral vertebra capped with an epiphysis 

 (T. J), below this is the down-turned outer end of the costal process of 

 that vertebra and at its outer lower angle a small epiphysis {A. C. i, 

 Fig. 2) is visible, next we see the down-turned outer end of the costal 

 process of the second sacral vertebra and at its lower and outer end 

 a small epiphysis {A. C. 2). Next is seen the costal process of the 

 third sacral vertebra having at its outer lower angle a small epiphysis 

 {A. C. 3). Similarly, an epiphysis more precociously developed is seen 

 at the lower outer angle of the fourth costal process {A. C. 4) and this 

 is at this time also in contact with the transverse process of the 5th 

 sacral vertebra. 



View from the side (Figs. 3 and 4). Two drawings are shewn 

 which are based on the appearances presented by six sacra of the age 

 of 18 years in my possession. It will be noticed that in the gaps 



Anat. Anz. XXX. Aufsätze. 



27 



