That a change in the character of the pulmonary structure so important as that just described should have attracted the notice of the physiologist, and been eagerly seized, as evidence in proof of the infant _having respired_, and therefore been _born alive_, cannot be a matter of surprise; and we accordingly find that the _hydrostatic test_ long enjoyed the unreserved confidence of the profession and the public. Whenever an infant was found dead, under circumstances of doubt and suspicion, its lungs were removed from the body, and immersed in water; if they sank, the subject of the experiment was immediately declared to have been still-born. If, on the contrary, they floated, it was concluded without farther enquiry, that the infant had lived after its birth. The aphorism of _Baglivi_ may be received as an expression of the general feeling so long entertained upon this subject. “_Pulmones fœtus mortui in utero matris, si extrahantur, et in aqua ponantur, petunt fundum; mortui vero extra uterum et aqua injecti innatent in ea. Quod signum ad infanticidia detegenda est evidentissimum._”[72] The number of innocent females who may have been thus sacrificed through a physiological conceit, is a circumstance that must excite the most awful reflection.[73] It is now well ascertained, and as generally admitted, that the validity of the _hydrostatic test_, as usually applied, must afford very unquestionable indications. _Bohn_,[74] _Hoffman_,[75] and _Heister_,[76] have shewn that the lungs of a fœtus, born dead, will under some circumstances, to be hereafter explained, float in water; while those of one that has lived after its birth may sink in the same fluid. _Dr. Gordon Smith_ is inclined to attribute _some_ of the uncertainty, by which the minds of medical men have been obscured with regard to the pulmonary tests, to confusion in the method of conducting the experiment, for there is, says he, but one order in which the steps can be taken, and if the anatomist should inadvertently resort to one stage of the process before another that should have preceded, he will baffle his own efforts. In commencing an examination of the thoracic organs, we should, previous to the disturbance of the parts, notice whether any morbid appearances present themselves, such as adhesions between the lungs and the pleura costalis, &c. We should at the same time observe whether the lungs be collapsed, or dilated, and whether they cover the lateral parts of the pericardium. We then proceed to separate the pulmonary organs from the body, in order to submit them to the _hydrostatic test_, to which we have adverted. For the performance of this dissection, _Dr. Hutchinson_ has given us so many complete and satisfactory directions, that we shall here introduce them for the instruction of the forensic physician. “Ligatures must be placed on the aorta and venæ cavæ, near their attachment to the heart; the trachea is