38 



gularity in the lumbar vertebrae we see an effort to imitate the usual 

 aspect of the region as nearly as may be in the spread of the trans- 

 verse processes. In cases of the last rib being like a transverse pro- 

 cess and there being only four lumbar vertebrie this appearance is 

 often very striking. It should not be understood that I would limit 

 this adaptation to the praesacral region. Ancel and Sencert may 

 be right in holding that the attachment of the 1st coccygeal to the 

 sacrum in the spines 764 and 478 is more than a coincidence. Un- 

 doubtedly adaptation is found behind the promontory of the sacrum 

 as well as before it. But it is of much less importance on account of 

 the increase of variations towards the posterior end of the spine and 

 of the difficulty that often exists of counting the coccygeal vertebne. 



A word may be said here about the so-called vertebra fulcralis 

 first proposed by Welcker and raised to a greater importance by Holl. 

 It is the vertebra which has the largest part in forming the auricular 

 surface for the iUum. I had observed several cases in which it was 

 most difficult to decide whether the 24th or the 25th really deserved 

 the title; but I, unlike Holl, had in some cases found it to be the 

 24th. I suggested that we could not expect absolute stability of the 

 fulcralis any more than of any other part of the organism. The im- 

 portance of the conception is that usually (not always) the fulcralis 

 is clearly the 1st sacral, and according to the views I have followed, 

 the one to be compared with the fulcralis of other columns and used 

 as a starting point. Further observations, published in this paper, 

 confirm my idea of the variation of the fulcralis. I now attach less 

 importance to this feature than I once did. There are several cases 

 in which it is doubtful whether the vertebra which must evidently be 

 called the 1st sacral is the fulcralis, and several in which I am sure 

 it is not. In other words a vertebra which can be nothing but the 

 1st sacral may vary in the share it has in forming the auricular sur- 

 face, just as it may in the development of its spinous process or in 

 the freedom of its transverse elements. In short this feature cannot 

 be taken as a criterion to determine whether a certain vertebra is 

 the 1st sacral or not. 



The only point in my conclusions which seems to me open to 

 serious question is that of irregular segmentation. I must own frankly 

 that the criticisms of Ancel and Sencert strike me as of great weight. 

 Certainly something is to be said for the theory. The python with 

 two vertebrae double on one side shows that such a thing can occur; 

 still it must be admitted that this is not a parallel case with what 

 .we see in the human spine. Baur's gavial with an extra presacral 



