As it is interesting, from this point of view, to compare the development of other Articulata with that of insects, I give a figure (Fig. 32), representing an early stage in the development of a spider (_Pholcus_) after Claparède,[23] who says, “C’est à ce moment qu’a lieu la formation des _protozonites_ ou segments primordiaux du corps de l’embryon. Le rudiment ventral s’épaissit suivant six zônes disposées transversalement entre le capuchon anal et le capuchon céphalique.” [Illustration: FIG. 33.—Embryo of _Julus_ (after Newport).] Among Centipedes the development of _Julus_ has been described by Newport.[24] The first period, from the deposition of the egg to the gradual bursting of the shell, and exposure of the embryo within it, which, however, remains for some time longer in connection with the shell, lasts for twenty-five days. The segments of the body, originally six in number, make their appearance on the twentieth day after the deposition of the egg, at which time there were no traces of legs. The larva, when it leaves the egg, is a soft, white, legless grub (Fig. 33), consisting of a head and seven segments, the head being somewhat firmer in texture than the rest of the body. It exhibits rudimentary antennæ, but the legs are still only represented by very slight papilliform processes on the undersides of the segments to which they belong. As already mentioned, it is possible that at one time the vermiform state of the Homomorphous insects—which, as we have seen, is now so short, and passed through at so early a stage of development—was more important, more prolonged, and accompanied by a more complete condition of the internal organs. The compression, and even disappearance of those embryonal stages which are no longer adapted to the mode of life—which do not benefit the animal—is a phenomenon not without a parallel in other parts of the animal or even of the vegetable kingdom. Just as in language long compound words have a tendency to concision, and single letters sometimes linger on, indicating the history of a word, like the “l” in “alms,” or the “b” in “debt,” long after they have ceased to influence the sound; so in embryology useless stages, interesting as illustrations of past history, but without direct advantage under present conditions, are rapidly passed through, and even, as it would appear, in some cases altogether omitted. [Illustration: FIG. 34.—Colony of _Bougainvillea fruticosa_, natural size, to the underside of a piece of floating timber (after Allman).]