513 



In comparing the results of the investigators who have published 

 statistical accounts of vertebral variations, noteworthy difierences are 

 apparent. For the sake of facilitating this comparison I have arranged 

 in the following table a summary of the results obtained. 



In all 1059 spinal columns are tabulated. Of these, 46 are from 

 embryos 13—50 mm long, 55 are from fetuses of the 3d to the 9th 

 month, 50 are from children of less than a year old, and 908 are 

 from adults. Among the „adult" skeletons are included, however, 

 a few skeletons of children over one year old. 



Of the total number of columns, 967 (91.3 %) have 24 presacral 

 vertebrae. In the negroes reported by Bardeen, in the adult male 

 skeletons reported by Bianchi and Steinbach, and in the fetuses 

 reported by Paterson, the percentage of spinal columns with 24 

 presacral vertebrae is nearer 80 "/o than 90%. On the other hand, 

 100% of the embryos reported from the His collection and 98% of 

 the children of a year or less studied by Steinbach, have 24 presacral 

 vertebrae. Of the skeletons specifically reported from white females, 

 133 out of 139 (95.7%) have 24 presacral vertebrae. In the corre- 

 sponding male skeletons, 144 out of 165 (87.3%) have the normal 

 number. Spinal columns with 23 or 25 presacral vertebrae are found 

 with about equal frequency, 4.3 to 4.4 7o of the total number. Stade- 

 RiNi and Bianchi found a greater percentage of reduced spinal columns 

 (7 — 9.2 7o); Ancel and Sencert and Steinbach a greater percentage 

 of extended adult columns (7 — 13 7o)- Paterson found an unusual 

 number of extended fetal colums (11 out of 30, 13.3 7o)- 



Into the further details it is unnecessary to go in this place, since 

 comparative data are yielded by the table. We may, however, draw 

 the following conclusions: 



1) After the attachment of the ilium to the vertebral column is 

 made it is not segmentally altered during subsequent development. 



2) Regional variation in the vertebral column is an inherited con- 

 dition which makes itself manifest early in embryonic development. 

 A sufficient number of individuals of a given race would probably 

 show the same frequency of regional vertebral variation throughout 

 the course of development from the sixth week to the adult condition. 

 The embryos in the collektion of Professor Mall show, however, an 

 unusually high percentage of „normal" vertebral columns, while those 

 in the collection of Professor Rosenberg show an unusual percentage 

 of variations. A similar difference in frequency of variation may be 

 seen by comparing the results of the observations of Paterson and 

 Steinbach on fetal spinal columns. 



Anat, Anz. XXV. Aufsätze. 33 



