Charles E. Bardeen 



277 



TABLE A. 



The lengths of the various regions of the spinal columns of embryos 

 OF the second and third months, and the proportional length of the 



THORACIC compared WITH THE OTHER REGIONS. 



1. This is the measurement recorded before the embryo was sectioned. The embryo was 

 cut sagittally. The length of the sections in the median line is 7.5 mm. The general de- 

 velopment corresponds with that of an embryo of this length. 



2. These figures represent the length of the pelvic portion of the spinal column. 



This table discloses considerable individual variation. The length of 

 the cervical region is about 60% of that of the thoracic. In Embryos 

 CIX, 1 and 2, this ratio is much exceeded. The measurements for CIX 

 are calculated from obliquely transverse sections and hence are subject to 

 some error. The data concerning the measurements for 1 and 2 are not 

 given by Aeby. 



The lumbar region, at first less than 40% in length of the thoracic, 

 in most embryos approximates 50%. The length of the sacral region 

 varies from 33 to 42.5% of the thoracic. The coccygeal region, with a 

 nearly constantly diminishing comparative length, shows marked varia- 

 tions. 



There is no good evidence that the straightening of the spinal column 

 is accompanied by a marked increase in relative length of the lumbar 

 region after the early stages in Embryos II and CIX. 



