PRIMORDIAL CRANIUM OF THE CAT 349 



centra in the mole were found to arise in connection with intra- 

 vertebral capsules, outside the sheath of the notochord. Further- 

 more, the relation of the neural arch of a vertebra to its centrum 

 differs from that between the lateral occipital arch and para- 

 chordal; in the former the parts are primarily independent, in 

 the latter continuous. On account of these discrepancies be- 

 tween vertebral and occipital chondrogenous development, 

 Noordenbos finds weak support for the vertebral theory in the 

 chondrocranium. He says (p. 373): ''Ich mochte aus diesen 

 Erscheinungen, im Gegensatz zur allgemein giltigen Auffassung, 

 schUessen, dass fiir das Chondrocranium die Wirbeltheorie nicht 

 aufrecht zu halten sei." But the vertebral theory, notwith- 

 standing the blows dealt it from the time of Huxley's attack to 

 the present, has shown itself tenacious of Ufe, and the thought 

 uttered by Oken more than one hundred years ago demands 

 deference of the worker of today. 



Recent investigations into vertebral development, (Bardeen, 

 Weiss, Weigner) demonstrate the presence of a pair of chondro- 

 genous centers, lying close to the midline and reacliing a some- 

 what higher level dorsally than the notochord, which grow to 

 surround the latter, and so form the cartilaginous vertebral 

 body. There is, in general, apparently a fundamental difference 

 in the original relation to the notochord of the parachordal plate 

 and vertebral centrum. At one spot, only, does the relation of 

 the parachordal to the notochord approach that of a vertebral 

 centrum, namely at the level of the anterior commissure; car- 

 tilage is here developed around the notochord. The discovery 

 of processes of chondrification in the perichordal sheath of the 

 occipital region, related eventually to the dens epistrophei and 

 which fulfill the conditions of vertebral central development in 

 general, have been mentioned. It would seem that the evidence 

 presented by these investigators (Weiss, Gaupp, Weigner) jus- 

 tifies the interpretation which has been put forward of rudi- 

 mentary centra in the occipital region. To this evidence must 

 be added that given by cat. By the interpretation of Weiss of 

 the hypochordal nature of the caudal part of the basal plate, 

 the objection to comparing the lateral occipital arch with the 



