222 
Görrr ') examined the development of the sternum in Cnemido- 
phorus spec. and in Anguis fragilis. In Cnemidophorus the first 
formation was paired and consisted of a triangular widening of the 
ventral end of the first (future) vertebro-sternal rib. This primitive 
formation developed caudally only so far as further ribs attached 
themselves to it, so not independently. Moreover Görre thinks it 
probable that the last cervical rib, which in the further development 
is more and more removed from the sternum, has also taken part 
in the first formation of the sternum. In Anguis the sternum was 
formed out of the widened end of the first rib, which soon after 
this was loosened from the sternum. 
Apparently the embryos examined by RatHkr were too old for 
the purpose. The results of WirprrsHrm’s *) examinations of Lacerta 
and Anguis agree very well with Görre’s experiences. Only he 
thinks it probable that also the last but one cervical rib takes part 
in the formation of the sternum. Also in crocodilus biporcatus the 
sternum, according to Wirpersneim, is formed by the ribs. 
SCHAUINSLAND *) deseribes the sternal formation in Sphenodon, first 
connected only with one rib, afterwards with three. Out of these 
one has to think the sternum has been formed. And, lastly, accord- 
ing to BocotsuBski *) the paired first sternal formation in Lacerta 
and Anguis is formed without any original connection with ribs, 
is therefore an autochthonie formation. In short, according to the 
generally prevailing opinion the sternum of the reptiles is formed 
out of the ribs*). Only Bogo.suBski supposes the sternal formation 
in the reptiles to be autochthonic. ; 
It is advisable to mention here that there are some more theories 
on the development of the sternum of higher amniota, the mammals. 
According to Paturson*) the first formation of the sternum consists 
of an unpaired, dense mass of mesoblastcells, lying in the median 
line. Later on one finds two sternal bands because the median part 
has become poorer in cells. The relation between ribs and sternum 
is secondary, on the other hand there is a primary connection 
between the median formation and the shoulder girdle. WuireHEAD 
and Wapper’) suppose the mammaliam sternun to be built out of 
1) A. Görre. Archiv. f. mikrosk. Anat. Bd. XIV, 1877. 
2) R. WIEDERSHEIM. Das Gliedmaszenskelett der Wirbelthiere. Jena, 1892. 
8) H. ScHAUINSLAND. Archiv. f. mikrosk. Anat. u. Entw.gesch. Bd. LVI, 1900. 
4) S. Boaousussk!. Zeitschr. f. Wissensch. Zool. Bd. 110, 1914. 
5) O. Hertwie’s Handb. d. vergl. u. experim. Entwickl.lehre. Jena. 
6) A. M. Paterson. Journ. of Anat. and Physiol. Vol. 35. 1900. 
7) R. H. Wurreneap and Wapper. Americ. Journ. of Anatomy. Vol. 12, 1911. 
