. The chordates. Chordata. Aim and Method of Comparative Anatomy 375 similarly located parts of the branchial skeleton of fishes, as did Saint-Hilaire and other early anatomists, in spite of their appreciation of "; Having observed where an organ is in the animal, the anatomist must next find out where it belongs. Figure 296 represents cross sections in the midtrunk region of two animals of different kinds. In '"I" there is a complete system of mesenteries extending from dorsal to ventral body-wall. An organ, "A," lies in the mesentery dorsal to the in
. The chordates. Chordata. Aim and Method of Comparative Anatomy 375 similarly located parts of the branchial skeleton of fishes, as did Saint-Hilaire and other early anatomists, in spite of their appreciation of "; Having observed where an organ is in the animal, the anatomist must next find out where it belongs. Figure 296 represents cross sections in the midtrunk region of two animals of different kinds. In '"I" there is a complete system of mesenteries extending from dorsal to ventral body-wall. An organ, "A," lies in the mesentery dorsal to the intestine, and a different organ, "B," is swung in the ventral mesentery. In the other animal, "II," is found an organ, "X," whose structure resembles that of "B," but "X" is dorsal to the intestine. Ventral to the intestine of "II" is an organ, "Y," which is structurally similar to "; Struc- tural similarity would indicate that "Y" is the same as "A," and "X" the same as "B," but "A" and "X" are alike in their dorsal location and "B" and "Y" in their ventral location. However, a study of con- neclions in "II" shows that " Y" lies in a broad sheet of mesentery ex- lending from the middorsal line to the intestine and "X" is supported by a membrane passing indirectly from the intestine to the midventral line. If the "A-i>i/es/me-B" system of "I" were rotated on the long axis of the intestine through an arc of 180°, without changing any attachments and with the consequent necessary expansion of the I II. 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 Rand, Herbert W. (Herbert Wilbur), 1872-1960. Phil
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