. The British woodlice, being a monograph of the terrestrial isopod Crustacea occurring in the British Islands. Crustacea -- Great Britain; Oniscidae; Anthropoda; Invertebrates. FIG. 32.—EMBRYO OF THE WOODLOUSE SHOWING THE THREE DIVISIONS OF THF. INTESTINE SEPARATELY DEVELOPED (PotCtlHo SCabft). AFTER ROULE. ffind-gut appendages have made their appearance and the mesoderm, (which has grown considerably, to form the beginnings of the muscles) has sent prolongations into each of tliem. About this time, spaces (see fig. 31) are formed in the muscular mesoderm which are all that remain of the true
. The British woodlice, being a monograph of the terrestrial isopod Crustacea occurring in the British Islands. Crustacea -- Great Britain; Oniscidae; Anthropoda; Invertebrates. FIG. 32.—EMBRYO OF THE WOODLOUSE SHOWING THE THREE DIVISIONS OF THF. INTESTINE SEPARATELY DEVELOPED (PotCtlHo SCabft). AFTER ROULE. ffind-gut appendages have made their appearance and the mesoderm, (which has grown considerably, to form the beginnings of the muscles) has sent prolongations into each of tliem. About this time, spaces (see fig. 31) are formed in the muscular mesoderm which are all that remain of the true body cavity characteristic of animals above the level of the jelly fish, and in these spaces the blood ultimately cir- ^^yf^-Y^^^^^ culates. The body next alters somewhat in shape and the three divisions of the intestine approach one another (see fig. 32) previous to their junction^ As may be imagined dur- ing these processes the food-yolk has gradually been used up and the space which it occupied taken by the internal organs, which we have mentioned. In the last stages of the development the ap- pendages become larger still, the heart makes its appearance, segmentation of the body is completed, and except that the seventh pair of walking legs are as yet rudimen- tary the woodlouse is completed. It is only after hatching that the pair of legs mentioned, attain to their normal length. The process of segmentation of the egg and the formation of its layers lasts about a fortnight, while the completion of the development proceeds much more rapidly, for another three weeks bring it to an end. After the first moult or change of skin the last pair of. •Hcahm &r /vr/n. FIG. 33.—EMBRYO OF THE WOODLOUSE SHOWING TRACES OF THE SEGMENTS {PorCtlHo SCaber). after Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectinverte, bookyear1906
