339 



Regions of the Spine. It seems beyond question that certain 

 vertebrae are capable of having the characteristics of those above 

 or below them in numerical order. The last coccygeal may be just 

 the same to all appearance, though its number from the atlas 

 may differ by several places. The last sacral and 1st coccygeal are 

 absolutely uncertain. As the vagaries of the 24th, 25th, 26th, and 

 even the 27th, any one of which may be the fulcralis, are at the 

 basis of the classification adopted in this paper, they need not be 

 discussed here, except in so far as the condition of a given vertebra 

 affects that of others, as for instance the effect of a certain vertebra 

 being the fulcralis on the two vertebrae above it and on the sacrum 

 as a whole. It is rather surprising that no effort has ever been made 

 to decide whether sacra could be distinguished one from another 

 according to the particular vertebra that happens to be the fulcralis. 

 From this series it would seem that there are certain peculiarities 

 which in most cases would enable us at the very least to separate 

 the sacra in which the 24th is the fulcralis, and those in which 

 it is strongly sacralized, from those in which the 25th or the 26th is 

 the fulcralis. On the other hand slight sacralization of the 24th 

 and 25th may be very similar. While it is Hkely that a larger series 

 would show more instances of difficult diagnosis, I think it would 

 confirm the deductions from the present one, which are as follows : 

 Distinctions between Spines with Sacra of different 



ji n u m e r i c a 1 Composition. 



i I. When the 26th is the fulcralis and the 25th more or less 

 sacralized, the promontory is perfectly evidently above the former, 

 and there is no secondary promontory. The 25th, apart from its 

 sacraHzation, is a good last lumbar, the disc below it, though much 



'diminished, is always present, and the 24th is always a penultimate. 

 (The spine of a child of ten (spine 21) is the only exception to this 

 rule. The promontory is not over-evident, nor is the possibihty of a 

 secondary one to be denied; but this, it is to be remembered, is a 

 characteristic of the pelvis of early childhood. Spine X is very dif- 

 ferent on the two sides, and I hesitate to affirm that, if looked at 

 from the right side only, there might not be doubt about the position 

 of the promontory.) 



II. When the 25th is quite free, the promontory is always un- 

 nistakably below it. The 25th and 24th are generally pretty typical 

 iltiraates and penultimates. 



III. When the 24th is sacralized more or less, but is not the 

 ulcralis, the position of the promontory is not clear, and some- 



22* 



