Detail, illustrating his statements by the preparations he exhibited, the progress of ossification in the sternum of the fowl and of the duck, pointing out how it differed in each, and giving his interpretation of the differences.
But it was now made to appear that the struthious birds in this respect resembled, not only the duck, but a great many other groups - waders, birds-of-prey, pigeons, passerines and perhaps all birds not gallinaceous - so that, according to Cuvier's view, the five points of ossification observed in the Gallinae, instead of exhibiting the normal process, exhibited one quite exceptional, and that in all other birds, so far as he had been enabled to investigate the matter, ossification of the sternum began at two points only, situated near the anterior upper margin of the side of the sternum, and gradually crept towards the keel, into which it presently extended; and, though he allowed the appearance of detached portions of calcareous matter at the base of the still cartilaginous keel in ducks at a certain age, he seemed to consider this an individual peculiarity.
Geoffroy here maintained that the five centres of ossification existed in the duck just as in the fowl, and that the real difference of the process lay in the period at which they made their appearance, a circumstance which, though virtually proved by the preparations Cuvier had used, had been by him overlooked or misinterpreted.
In their case the sternum begins to ossify from three very distinct points - one of which is the centre of ossification of Nitzsch's grouping.
A variety of other causes contributed to its decay: the opening up of new trade routes, the gradual ossification of the gilds into close and corrupt corporations, above all the wars in the Netherlands, the Thirty Years' War, and the Wars of the Spanish and Austrian Succession.
Moreover, the author goes on to remark that in adult birds trace of the origin of the sternum from five centres of ossification is always more or less indicated by sutures, and that, though these sutures had been generally regarded as ridges for the attachment of the sternal muscles, they indeed mark the extreme points of the five primary bony pieces of the sternum.
Prefrontal bones are absent; post-frontals are possibly indicated by a frequently occurring separate centre of ossification in the postorbital process, to which the frontals always contribute.
In the Gallinae the five well-known pieces or centres of ossification are said to consist of the two side-pieces of the second or middle series, and the three of the posterior.
In the ostrich and its allies no trace of this median centre of ossification ever occurs; but with these exceptions its existence is invariable in all other birds.
The principal theory which he hence conceived himself justified in propounding was that instead of five being (as had been stated) the maximum number of centres of ossification in the sternum, there are no fewer than nine entering into the composition of the perfect sternum of birds in general, though in every species some of these nine are wanting, whatever be the condition of development at the time of examination.