or be emphysematous in nature. Apart from the difficulty of artificially inflating the lungs of an infant in situ in cases of infanticide, nothing of that kind would be attempted, since it would be the object of the defendant to prove that the infant had been born dead, and not alive. As a general rule, there is no great difficulty experienced in determining whether the buoyancy of a lung is due to air inspired or to gases developed within it through putrefaction, since the air in the latter case is not found in the air-vesicles of the lungs, but in the cellular tissue and in the form of large bubbles, which disappear completely under pressure. Moreover, lungs in a state of putrefaction differ in appearance very much from healthy lungs, being greenish-yellow in color, having but little consistence, and emitting a fetid odor. It may be mentioned, also, in this connection, that as the lungs of the infant do not putrefy as rapidly as the other organs, if these organs are found undecomposed, then any buoyancy exhibited by the lungs could not be due to putrefaction. As it is very doubtful whether emphysema is ever spontaneously developed in the lungs of an infant, the objection that the air in the lungs could be developed in this way is without foundation. On the other hand, it may be objected that the fact that the lungs sink when immersed in water does not necessarily prove that the infant had not breathed, since the unaerated condition of the lungs might be due to disease. While it is true that the density of the lungs will be so much increased by pneumonia or congestion that they will sink in water, these diseases occur so rarely in new-born children that but little importance need be attached to such an objection. Notwithstanding that the value of the hydrostatic test has been questioned, that it cannot be expected to prove absolutely that the child has breathed, still less been born

alive, medico-legally, yet if the lungs of an infant do float in water, the examiner will be warranted, under ordinary circumstances, in stating that the infant had breathed, and in all probability had been born alive. The test of an infant having been born alive, or rather of having breathed, based upon the changes undergone by the heart and certain blood vessels, after respiration has been established, and known as the docimasia circulationis, is of rather limited application, as will become apparent when the differences between the foetal and adult circulations are considered.

Foetal Circulation.—The principal peculiarities in which the circulation of the fœtus differs from that of the adult are that little or no blood flows through the lungs of the fœtus, the placenta being the organ by means of which the blood is aerated, and that the right side of the heart communicates with the left, the blood being, therefore, neither arterial nor venous, as in the adult, but mixed. In the fœtus (Pl. 3), part of the blood flows directly from the right auricle through the foramen ovale into the left auricle, instead of indirectly by the right ventricle, pulmonary artery, lungs, and pulmonary veins; part of the blood from the right ventricle through the pulmonary artery by the ductus arteriosus into the aorta. Further, the blood flows in the foetus from the placenta by the umbilical vein, and its continuation the ductus venosus, to the vena cava and to the right side of the heart, and thence through the latter as just described, little or none going to the lungs, to the aorta, and so back by the umbilical arteries to the placenta. Such being the main features of the fœtal circulation, with the inspiration of air and the separation of the infant from the placenta by division of the umbilical cord the foramen ovale closes, the umbilical vessels, the ductus arte

Diagrammatic View of Foetal Circulation: a, arch of the aorta; a', its dorsal part; a", lower end; ves, superior vena cava; vci, inferior vena where it joins the right auricle; vci', its lower end; s, subclavian vessels; j, right jugular vein; c, common carotid arteries; four curved dotted arrow-lines are carried through the aortic and pulmonary opening, and the auriculo-ventricular orifices; da, opposite to the one passing through the pulmonary artery, marks the place of the ductus arteriosus; a similar arrow-line is shown passing from the vena cava inferior through the fossa ovalis of the right auricle, and the foramen ovale into the left auricle; hy, the hepatic veins; up, vena portæ; X to vci, the ductus venosus; uv, the umbilical vein; ua, umbilical arteries; uc, umbilical cord cut short; i, i, iliac vessels.

riosus, and the ductus venosus shrivel up, and, ceasing to be pervious, become fibrous cords. The blood then flows through the heart and lungs, and the adult circulation is established.

Under ordinary circumstances, if the foramen ovale, ductus venosus, and ductus arteriosus are found open, the examiner would be warranted in stating that the foetus had not been born alive, and that, therefore, in all probability, if any crime had been committed, it would be that of fœticide, and not of infanticide. Not unfrequently, however, several days or even weeks may elapse before the blood ceases to flow through these vessels, and as the foramen ovale may remain, under certain circumstances, open through life, obviously too much importance must not be attached to the open or closed condition of the heart and vessels as evidence of the infant having been born dead or alive. The drying up of the part of the umbilical cord remaining attached to the umbilicus after division, that usually takes place within two or three days after delivery, together with its subsequent separation and cicatrization, may be regarded as proof of the child having been born alive, since, although the cord withers and dries up in a child born dead as well as in one born alive, it always remains attached in the former to the umbilicus, never separating spontaneously. The liver of the fœtus is larger than that of a recently born infant, and that of the infant is larger than that of an eight or ten months old child.

Liver and Contents of the Stomach in a New-born Child. -Too much importance, however, must not be attached to the size of the liver as positive proof of the infant having breathed, since the difference in the size of the liver in a recently born child, as compared with its size