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Updated: June 15, 2025
These unite with the masses of cartilage surrounding the notochord to form cartilaginous vertebræ, which may be stiffened by an infiltration of carbonate of lime. The vertebral column of sharks has reached this stage. Then the cartilaginous vertebræ ossify and form a true backbone. I have described the process as if it were very simple.
Now this is a very peculiar origin for cartilage, and the notochord is a very strange cartilage even if we have not made a mistake in calling it cartilage at all.
Our circulation begins as a veritable fish circulation; our earliest skeleton is a notochord; Meckel's cartilage, from which our lower jaw and the bones of our middle ear develop, is a whole genealogical tree of disagreeable ancestors. Our glandula thyreoidea has, according to good authorities, an origin so slimy that it should never be mentioned in polite society.
In most modern fishes and in all higher vertebrates the notochord is gradually removed as the bodies of the vertebrae are formed about it; but in the Devonian fishes it persists through maturity and the vertebrae remain incomplete. THE SKELETON IS CARTILAGINOUS. This also is an embryological characteristic.
There is always, to begin with, an egg having the same essential structure as that of the Dog: the yelk of that egg always undergoes division, or 'segmentation' as it is often called: the ultimate products of that segmentation constitute the building materials for the body of the young animal; and this is built up round a primitive groove, in the floor of which a notochord is developed.
There is always, to begin with, an egg having the same essential structure as that of the Dog: the yelk of that egg always undergoes division, or 'segmentation' as it is often called: the ultimate products of that segmentation constitute the building materials for the body of the young animal; and this is built up round a primitive groove, in the floor of which a notochord is developed.
The chordoma is a rare form of tumour originating from the remains of the notochord in the region of the spheno-occipital synchondrosis or in the sacro-coccygeal region. Diagnosis of Sarcoma. A sarcoma is to be differentiated from an inflammatory swelling such as results from tubercle, actinomycosis, or syphilis, from an innocent tumour, and from a cancer.
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