NUMERICAL VARIATION IN THE HUMAN SPINE. 243 



tion or by an arrest of development. This latter is caused mostly by unknown accidental 

 disturbances manifested by irregular distribution of the developmental energy. Varia- 

 tions depend on the power to vary about a mean, so that they give a false suggestion of a 

 progressive or a retrogressive developmental tendency." 



I am strongly inclined to agree with Kohlbrugge on most points ; but I accept evolu- 

 tion, with certain limitations, as the best working hypothesis, although I regard as by no 

 means proved, nor even probable, that its course has been by a gradual succession of 

 minute changes. Still less do I believe that the human body is, as it were, in a state of 

 oscillation between reversive and progressive variations. Finally, I can see no contra- 

 diction between evolution on the one hand, and design and teleology on the other. While 

 I shall draw from this series of specimens such conclusions as seem to me justified, I hope 

 that the description will prove sufficiently accurate for those who do not agree with me 

 to make use of them also. 



Anatomical Points. — I beg leave to recall the arrangement of the transverse p7-oc- 

 esses of the lumbar region, as they will be repeatedly referred to. Their spread increases 

 up to the 3d. Those of the 4th or penultimate vertebra are shorter, and lighter, with 

 a peculiar shape caused by the lower border running obliquely upward to the tip. They 

 also spring more from the pedicle than those above them. The 5th transverse processes 

 are thicker. They arise still more ventrally, and imply an approach to a combination 

 of transverse process and costal element, as is seen in the young sacrum. Their length is 

 uncertain. They are longer than those of the 4th, and may equal those of the 3d. Thus 

 both the lowest lumbar vertebrae are chai'acteristic. 



The 3d Sacral Vertebra usually has a transverse line across the body at about its 

 middle, indicating a change in direction of the anterior surface of the sacrum. Hermann v. 

 Meyer beUeved that a Une fi'om the top of the symphysis to the middle of this vertebra is at 

 a more constant angle to the horizon than that to the promontory. He accordingly called 

 it the conjucjata vera. I have taken the liberty of associating this conjugata with the 

 transverse line which, I think, is a criterion of a normal 3d sacral. When, therefore, I say 

 that the 3d sacral bears the conjugata vera, I mean that this transverse hue is evident. 



The vertebra fulcralis being accepted as a starting point, and the number of coccygeal 

 vertebrae being disregarded as too uncertain, the following classification resting on the 

 number of praesacrals and on the condition of the last lumbar, has been adopted. 



