Vertebrates, which has been evolved from that of the Selachii, five consecutive sections are discoverable at a certain early period of development, and one might be induced to trace these to five primitive vertebrae; but these sections are due entirely to adaptation to the five primitive cerebral vesicles, and correspond, like these, to a large number of metamera. ❋ Ernst Heinrich Philipp August Haeckel (1876)
The body is a series of metamera, as several of the primitive segments are developed. ❋ Ernst Heinrich Philipp August Haeckel (1876)
The gill-clefts, which originally in the older acrania pierced the wall of the fore-gut, and the gill-arches that separated them, were presumably also segmental, and distributed among the various metamera of the chain, like the gonads in the after-gut and the nephridia. ❋ Ernst Heinrich Philipp August Haeckel (1876)
But as far as our present task -- the derivation of the simple body of the primitive vertebrate from the chordula -- is concerned, the articulate parts or metamera are of secondary interest, and we need not go into them just now. ❋ Ernst Heinrich Philipp August Haeckel (1876)
The number of the metamera, and of the embryonic somites or primitive segments from which they develop, varies considerably in the vertebrates, according as the hind part of the body is short or is lengthened by a tail. ❋ Ernst Heinrich Philipp August Haeckel (1876)
In the developed man the trunk (including the rudimentary tail) consists of thirty-three metamera, the solid centre of which is formed by that number of vertebrae in the vertebral column ❋ Ernst Heinrich Philipp August Haeckel (1876)
Both sets are segmented, and consist of a double row of muscular plates (Figures 1.98 and 1.99 ms); the number of these myotomes determines the number of joints in the trunk, or metamera. ❋ Ernst Heinrich Philipp August Haeckel (1876)
In all the vertebrates and articulates the developed individual consists of a series of successive members (segments or metamera = "parts"); in the embryo these are called primitive segments or somites. ❋ Ernst Heinrich Philipp August Haeckel (1876)
But to complete our picture we must also consider the segmentation or metamera-formation of them, which has yet been hardly noticed, and which is seen best in the longitudinal section. ❋ Ernst Heinrich Philipp August Haeckel (1876)
All the chief parts of the body are now laid down: the head with the primitive skull, the rudiments of the three higher sense-organs and the five cerebral vesicles, and the gill-arches and clefts; the trunk with the spinal cord, the rudiment of the vertebral column, the chain of metamera, the heart and chief blood-vessels, and the kidneys. ❋ Ernst Heinrich Philipp August Haeckel (1876)
In man and all the more advanced vertebrates the body is made up of a series or chain of similar members, which succeed each other in the long axis of the body -- the segments or metamera of the organism. ❋ Ernst Heinrich Philipp August Haeckel (1876)
However, the composition from these pro-vertebrae or internal metamera is usually, and rightly, put forward as a prominent character of the vertebrate, and the manifold division or differentiation of them is of great importance in the various groups of the vertebrates. ❋ Ernst Heinrich Philipp August Haeckel (1876)
In the tailless or anthropoid apes the number of metamera is much the same as in man, only differing by one or two; but it is much larger in the long-tailed apes and most of the other mammals. ❋ Ernst Heinrich Philipp August Haeckel (1876)
As this internal articulation or metamerism is mainly found in the vertebral column and the surrounding muscles, the sections or metamera were formerly called pro-vertebrae. ❋ Ernst Heinrich Philipp August Haeckel (1876)
