When the vertebrae are free their 6.h, centra articulate with each other by complicated joints, exhibiting four types.
Later those pads fuse with the anterior end of the centrum of the vertebra to which they belong; where the vertebral column is rendered inflexible, the disks are ossified with the centra and all trace of them is lost.
The centra] government depended ultimately on the armed support of th two great powers; to quarrel with those would be to ruin th constitution, or at best to play into the hands of the extrem revolutionists.
The forms of batrachians with which we are acquainted show the vertebral column to have been evolved in the course of time from a notochordal condition with segmented centra similar to that of early bony ganoid fishes (e.g.
Eurycormus), to biconcave centra, and finally to the socket-and-ball condition that prevails at the present day.
Embolomeri, with the centra and intercentra equally developed disks, of which there are thus two to each neural arch; these disks perforated in the middle for the passage of the notochord.
As a matter of fact, these vertebrae have no centra proper, that part which should correspond with the centrum being formed, as a study of the development has shown (H.