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the various circumstances that impair and weaken its conclusiveness, it is impossible he can have any distinct idea either of its force or its fallacy.
Suppose a charge of infanticide—a crime that from its very nature scarcely admits of any other kind of proof, and which indeed, from the neglect of the study of Medical Jurisprudence in this country, almost always escapes with impunity—what is the medical evidence generally necessary in such a case? First, proof that the child was born alive; second, that its death was the result of criminal violence; and lastly, that the accused was delivered at a period corresponding to the age of the child. These facts are capable of being established in certain cases in the most conclusive manner from an examination of the child and the mother. But this requires much knowledge and skill, and a careless or inexperienced practitioner conducting such an investigation is liable to fall into the greatest errors. Take the first step in the inquiry—proof that the child was born alive, without which the indictment cannot be sustained, and which can scarcely ever be proved by any other than indirect evidence. This evidence is here derived from certain changes that take place in the system of the child, and which are the necessary result of the changed condition of the being, the moment it passes from the womb to an independent state of existence. Thus the lungs, that during the whole period of intra-uterine life he unmoved in the chest, undergoing no change but the slow one of nutrition and growth, are at once at birth called into a state of activity, which is to continue unceasingly as long as life itself; they are expanded with the air which rushes in from without, and are now for the first time filled with blood, which, abandoning its former course, leaves the channels through which the communication between the child and mother was maintained, dry and shrunken. It is chiefly from the alterations thus produced in the size, aspect, absolute and specific weight of the lungs, that the medical witness draws his conclusions. But changes similar to the most characteristic of these may be produced by other
