. The anatomical record. Anatomy; Anatomy. 338 FRANKLIN PEARCE REAGAN sac a portion of the embryonic bod}' bounded dorsally bj' ecto- derm and ventrally by entoderm (fig. 9). The cut edges pro- duced by the longitudinal incision have fused, the point of fusion being indicated by the apex of the projection on the left side in figure 9. In this figure we have a photograph of a 'projecting' head; the section passes through the anterior part of the mid- brain region, presenting a rather puzzling condition in that it is entirely devoid of fore-gut. Two large dorsal aortae are pres- ent; the larger
. The anatomical record. Anatomy; Anatomy. 338 FRANKLIN PEARCE REAGAN sac a portion of the embryonic bod}' bounded dorsally bj' ecto- derm and ventrally by entoderm (fig. 9). The cut edges pro- duced by the longitudinal incision have fused, the point of fusion being indicated by the apex of the projection on the left side in figure 9. In this figure we have a photograph of a 'projecting' head; the section passes through the anterior part of the mid- brain region, presenting a rather puzzling condition in that it is entirely devoid of fore-gut. Two large dorsal aortae are pres- ent; the larger one is located on the side containing the greater amount of mesenchyme; correlated also with the fact that the. Fig. 9 Photograph of a section through the midbrain of the same meroplast as in figure S. show'ng we!! developed dorsal aortae and the absence of a tubular pharynx in a tubular head. Fusion of entoderm and ectoderm at points indicated by X (X 120). /, ectoderm; g, entoderm; /(, dorsal aorta; i, midbrain. incision on this side was made at a greater distance from the median line. Both aortae are bounded by distinct and unmis- takable endothelium. In the aortic cavities blood plasma has coagulated. No coelomic pouches are present in this section. Pleart-formation has not taken place in this particular experi- mental casei The phenomena under consideration are not to be regarded as regenerative changes. The head does not regenerate the yolk-sac, neither does the yolk-sac regenerate the head. In figures 6 and 7 it will even be seen that portions of the head itself were not regenerated. There is a genesis of the first order in. 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 Bardeen, Charles Russell, 1871-1935, ed; Boyden, Edward A. (Edward Allen), 1886-1976; Bremer, John Lewis, 1874- ed; Hardesty, Irvin
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1906
