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Updated: May 24, 2025
In this way we get the spherical, mulberry-shaped body, which we call the morula. The segmentation of the Amphioxus is not entirely regular, as was supposed after the first observations of Kowalevsky . It is not completely equal, but a little unequal.
Thus, then, there is something to be said in opposition to both the aggregational and the mechanical explanations of serial homology. The explanations suggested are very ingenious, yet repose upon a very small basis of fact. Not but that the process of vertebral segmentation may have been sometimes assisted by the mechanical action suggested.
In course of time this tribe falls into several by the process of segmentation, which in turn reunite in a confederacy. Such a confederacy is a growth, through the tribe and phratry, from a pair of gentes. The Chickasas are organized in two phratries, of which one contains four and the other eight gentes, as follows: I. Panther Phratry. Gentes. Wild Cat 2. Bird. 3. Fish. 4. Deer.
These gentes were usually such as had been formed by the segmentation of an original gens. The phratry existed in a large number of the tribes of the American aborigines, where it is seen to arise by natural growth, and to stand as the second member of the organic series, as among the Grecian and Latin tribes.
Again, the processes of development presented by some of these creatures do not by any means point to an origin through the linear coalescence of primitively distinct animals by means of imperfect segmentation. Again, Nicholas Wagner found in certain other Diptera, the Hessian flies, that the larva gives rise to secondary larvæ within it, which develop and burst the body of the primary larva.
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.
Its carapace is but slightly compressed laterally and hairy, as in Sacculina purpurea; the adherent feet are of considerable size, and the natatory feet are wanting, as, in the adult animal, are the corresponding cirri. As I learn from Mr. Powell in the Mauritius. Eggs of Tetraclita porosa in segmentation, magnified 90 diam.
The organism which has issued from the egg is a boat-shaped body with a fin-shaped limb pointing backwards on the ventral face, formed by the junction of the two fore-limbs. The segmentation of the body is very clear, especially on the abdomen. The whole body is perfectly smooth, without the least suspicion of hair.
This process of segmentation continues to go on downward till the whole yolk is taken in. These myriad cells are in fact the component parts of the little Turtle that is to be.
They were separated from one another by geographic, ethnic, ideological and political barriers which were intensified by tradition, custom, migration, and the competitive struggles among the elite for pelf and power. Ignorance and superstition played a major role in the decentralizing process. Conflicts at various levels led to further social segmentation and isolation of autonomous social groups.
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