1. The lungs may sink as a result of disease. 2. Respiration, even in healthy lungs, may be so imperfect that they may sink. 3. Emphysema pulmonum neonatorum. 4. Putrefaction. 5. Artificial inflation. 1. That in consequence of disease the entire lungs, or portions of them, may sink, and yet respiration may have taken place. Disease of the lung may occur previously to birth or soon afterwards, but it is scarcely probable that the disease would attack every portion of the lung. Parts, doubtless, small in proportion to the diseased part, may yet have been sufficiently inflated to float. The presence of disease is also not difficult of detection. 2. That respiration, even in healthy lungs, may be so imperfect that they may sink. This objection can scarcely be considered valid against the general application of the test, for in these cases there is no known test by which respiration or its absence can be determined. They are, therefore, out of the pale of the test, as they are out of every other mode of investigation. 3. _Emphysema pulmonum neonatorum._--Emphysema is generally the result of excessive dilatation of the air cells of the lung, rupture of the cell walls, and infiltration of the intra-lobular areola tissue. This condition may be brought about by: (_a_) Respiration. (_b_) Inflation. The fact of the matter is simply this, that the so-called _emphysema pulmonum neonatorum_, or emphysema of new-born children, is nothing more or less than incipient putrefaction, induced by certain unascertained conditions. Casper sums up his conclusions on this subject in the following words: “That not one single well-observed and incontestable case of emphysema, developing itself spontaneously within the lungs of a fœtus born without artificial assistance, is known; and it is not, therefore, permissible in forensic practice to ascribe the buoyancy of the lungs of new-born children, brought forth in secrecy and without artificial assistance, to this cause.” 4. _Putrefaction._--It must be admitted as proved that the lungs of new-born children in a state of decomposition will float in water. But this admission does not render the test valueless, for it must be remembered: (_a_) That air generated by putrefaction is found in bubbles _under_ the pleuræ, or in the fissures between the _lobuli_ of the lungs, and _not in the air cells_ of the lungs. (_b_) That gas as a result of putrefaction can easily be removed by compressing the lungs, or portions of them. (_c_) That crepitation in putrefied lungs is absent, owing to the fact stated under (_a_). (_d_) That the lungs are among those organs which putrefy late. (_e_) That negative evidence may be obtained, if the lungs, in a highly putrescent body, sink in water. The tendency of putrefaction, as above stated, is to cause them to float.