rubber tubing attached to a wooden base and to two upright ends.As illustrating the outer walls and structures of the embryonic heart, there was a series of enlarged photomicrographs of cross-sections made by the vriter at different levels through the heart of a 10-mm. pig embryo, showing the spongy ventricular musculature, the incomplete auricular and interventricular septa, the large valvulae venosae dextra et sinistra, and the different antero-posterior planes on wNhich the mitral and tricuspid orifices lie in relation to the orifices of the great trunks; also a photostat enlargement of a plate from Prentiss and Arey's Emnbryology, showing cross-sections through the hearts of human embryos of 6 mm., 9 mm., and 12 mm. Following these were diagrams from Spitzer illustrating his theory of incomplete torsion of the bulbar part of the heart as the main factor in the causation of the graver cardiac anomalies; and a photostat enlargement of the heart from a case of the so-called " tetralogy of Fallot." This section closed with a comparative anatomy series showing both pictorially and in specimens the hearts of the teleost, elasmobranch (skate), and Lepidosteus fishes, and those of the mud-puppy (necturus), python, turtle, and crocodile, all of which show, in certain features at least, successive stages in development of the human embryo, and therefore throw light on the stage at which arrest has occurred in some of the more complex of the cardiac anomalies.
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