AND THE DEVELOPMENT OF THE MYRIAPODA. 117 



their coverings, and these were followed by others in quick succession ; but so feeble 

 at first were their efforts, after throwing off the envelope, that scarcely any motion 

 could be perceived in them. The embryos thus passed from their apparently inani- 

 mate to an animated state of existence ; from a condition in which they seemed merely 

 to vegetate, endowed with no voluntary or instinctive powers, but, like the vegetable, 

 formed entirely of an aggregation of cells, totally incapable of spontaneous motion, 

 — to one in which they became active beings, gradually acquiring voluntary and in- 

 stinctive faculties, both as regards the means of procuring nourishment and of pre- 

 serving themselves from injury. Short indeed is the transition from a mass of uni- 

 form and inanimate cells, to the development into an active being, endowed with 

 its peculiar instincts. 



In less than ten hours from the commencement of this last change, the whole of the 

 embryos had burst and thrown off the amnion. Those in which the funis had not 

 been separated, now left their covering still connected by it to the shell. 



In about an hour after leaving the amnion (fig. 10.), the young lulus exhibited a 

 marked change. Its head was elongated on the prothorax (2.), the parts of the mouth 

 were distinctly moveable, and the eye, a single ocellus on each side of the head, ac- 

 quired a darker colour. Each antenna was composed of six distinct joints, of which 

 the third was much the longest, and the two apical ones were short, and sunk one 

 within the other. The whole body had been increased at least one-fourth in bulk 

 since leaving the amnion. It now measured about a line in length, and exhibited 

 very distinctly the nine original segments. The seven anterior of these were strongly 

 marked. In the germinal space {7-f), between the original seventh and eighth seg- 

 ments, six new segments were now developed. These were still very small, the length 

 of the whole being equal only to that of one of the original segments. At the present 

 time they did not form independent divisions of the body, but were covered by the 

 common tegument, and thus appeared like supplementary parts of the seventh seg- 

 ment, produced from the germinal membrane, and interposed between the seventh 

 and the penultimate segment (8.), which, as before stated, is a permanent segment 

 throughout the life of the animal. This latter fact shows that it is not merely by an 

 elongation and division of the terminal segment that the body of the lulus is deve- 

 loped, but that it arrives at its perfect state by an actual production of entirely new 

 segments ; that these are new growths or formations which are in progress long be- 

 fore they are apparent to the eye ; and that the original segments of the ovum, into 

 which the animal is first moulded, are permanent segments throughout its whole life. 

 But still more curious is it, that not only have new segments been formed as de- 

 scribed, but that the common tegument by which they are now covered, and which 

 also invests the whole body as the true skin, has already begun to be detached, pre- 

 paratory to its being thrown off, as is shown in the fact that the new segments are now 

 seen beneath it ; and it is further remarkable, that this deciduation of the fii*st skin 

 of the animal had actually commenced before the bursting of the amnion. These cir- 



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