. Outlines of zoology. Zoology. •. / V'"'j i-'\ ""^. Fig. 41.—Development of Hydra. (After Brauer.) I. sp., spermatozoa. 2. Amccljoid ovum ; }.^ germinal vesicle or nucleus ; ^ yolk spherules. 3. Ovuin with lobed envelope {sh) around it. 4. Ovum protruding; «., the nucleus ; tr/., the ruptured ectoderm ; cnd.^ the endoderm. 5. Section of blastosphere—£c/., ectoderm; End., endoderm— being formed. 6. Section of larva. Ect., ectoderm ; End., endoderm ; , gut- cavity ; sh., ruptured envelopes. slowly. Interstitial cells arise in tlie ccloderra ; a middle lamella is formed
. Outlines of zoology. Zoology. •. / V'"'j i-'\ ""^. Fig. 41.—Development of Hydra. (After Brauer.) I. sp., spermatozoa. 2. Amccljoid ovum ; }.^ germinal vesicle or nucleus ; ^ yolk spherules. 3. Ovuin with lobed envelope {sh) around it. 4. Ovum protruding; «., the nucleus ; tr/., the ruptured ectoderm ; cnd.^ the endoderm. 5. Section of blastosphere—£c/., ectoderm; End., endoderm— being formed. 6. Section of larva. Ect., ectoderm ; End., endoderm ; , gut- cavity ; sh., ruptured envelopes. slowly. Interstitial cells arise in tlie ccloderra ; a middle lamella is formed ; a gastric cavity liegins to appear in the midst of the endoderm. Thereafter the shell Ixtrsts, and development proceeds more rapidly. The etiibryo elongates, acquires a mouth by rupture at the distal (some- times called vegetative) pole. The inner sheath is also lost, and the young Hydra fixes itself and begins to live as its parent or parents did. The multipolar formation of the endoderm is perhaps a primitive. 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 Thomson, J. Arthur (John Arthur), 1861-1933; Newbigin, Marion I. (Marion Isabel), 1869-1934; Smith, Preserved, 1880-1941. fmo. New York, D. Appleton & Co.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
