. The biology of twins (mammals) . Twins. 76 THE BIOLOGY OF TWINS bryos. They would also never establish a nutritive con- nection with the placenta. A drawing of a wax model (Fig. 27) made from an ectodermic vesicle from which numerous embryonic outgrowths are being given off shows two outgrowths that give promise of ruditnentation. Embryonic out- growth 9 has evidently been produced too high up or too close to the original apical end of the vesicle and. Fig. 31.—^A group of primitive streak embryos of D. hybridus show- ing how some of the ectodermic outgrowths (F and IT) fail to secure attach
. The biology of twins (mammals) . Twins. 76 THE BIOLOGY OF TWINS bryos. They would also never establish a nutritive con- nection with the placenta. A drawing of a wax model (Fig. 27) made from an ectodermic vesicle from which numerous embryonic outgrowths are being given off shows two outgrowths that give promise of ruditnentation. Embryonic out- growth 9 has evidently been produced too high up or too close to the original apical end of the vesicle and. Fig. 31.—^A group of primitive streak embryos of D. hybridus show- ing how some of the ectodermic outgrowths (F and IT) fail to secure attachment to the endodermic parts of the egg. This may account for the rudimentary embryos seen in Figs. 29 and 30. (After Fernandez.) has not been able to grow out as rapidly as the rest; embryo 2 is small and apparently subsidiary to i and would probably have been rudimentary. Rudimentary embryos that are no more than formless masses of tissue attached by amniotic connecting canals with the common amnion are shown in Fig. 29. Here also are shown marked irregularities in the interrelations of embryos, as indicated by the forking of amniotic 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 Newman, Horatio Hackett, b. 1875. Chicago, Ill. : The University of Chicago Press
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