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which it was founded. If such a course had been pursued with regard to the uncertainty of the tests employed in the analysis of poisons, the science of toxicology would now be, what it was but a few years since, a mere shadow: and as,

in every subject connected with medicine, old and unfounded prejudices are rapidly sinking before the light of experience, we may hope that this branch of medical evidence will not long remain in its present unsatisfactory condition.

We have here, then, taken the most extreme view of the "objection” on the ground of putrefaction; but we will now consider that the process has not advanced so far as has been represented. In cases of this description it will commonly be found, where putrefaction has extended to the lungs, that air is collected beneath the pleura in large vesicles, as also that the central portions of the organ are perfectly destitute of air, and therefore sink: although, those taken from near the surface may have sufficient buoyancy to enable them to Hoat when immersed in water. * It is also found that, compression, these last-named portions may be deprived of their air, and be made to sink. The canalis arteriosus must be found pervious, and of equal diameter throughout; the foramen ovale open; and the skin of the umbilical cord perfectly continuous with that of the abdomen, presenting around the margin of its insertion no appearance of inflammation or ulceration. What is the conclusion which the medical jurist is justified in drawing from these facts? I presume that not even the most sceptical would hesitate to admit that they clearly prove that the child in question had not performed the act of respiration, and, therefore, according to law, that it had not lived. It might be said the child may have respired, and yet the quantity of air introduced have been so smallt as to become readily forced out by compression. This objection, however, could only create any difficulty in the most advanced cases of putrefaction, where the air, generated by this process, is retained within the central structure of these organs; for, in the case of which I am now speaking, the air is supposed to be distributed, as in incipient putrefaction, in large vesicles over the surface of the pulmonary structure, and not in the central portions. Now, if it had been introduced by respiration, it will be found, previous to submitting the divided portions of the lung to compression,

* I here presume that the lungs are healthy; for it is undoubtedly true that some diseases may harden their structure, after the establishment of respiration, to such an extent as to deprive them of their usual buoyancy.

+ Vide page 366.

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that the air is not diffused in large vesicles over the surface, but contained in the minute cells of the internal portions; and, moreover, that the condition of buoyancy is precisely reversed; for those taken from the surface will sink, while the central portions will float. Therefore, it will be perceived, even allowing it to be possible that respired air can be forced out by compression, which is of itself doubtful, we have still in our hands means of determining the question.

Those who have argued against the hydrostatic test, as being liable to lead to the condemnation of the mother, when innocent, in bringing forward the above objection have proved too much for it will be immediately apparent that, in cases of feeble respiration, if we can expel the air, as in cases of incipient putrefaction, without for the present dwelling upon its precise situation, we are led to draw the inference that a child, which may have merely made a single gasp on its entrance into the world, was born dead; in which case it is clear that the mother, so far from incurring a risk of her life, will be acquitted.

It is absolutely necessary, in order to unravel the intricacies involved in this subject, to pursue it through allits ramifications, and to combat the objections as they arise. It is my object, however I may act up to it, to shew not only the advantages, but the disadvantages, which are likely to result from employing this test as a means of investigation; and I am as little anxious to exaggerate its merits, as I am to conceal its defects. Nevertheless, it is impossible to allow idle or unmeaning objections to obscure those points which are really useful, or to give strength to those which are apparently defective, when the whole may be proved to be groundless, by adopting a proper method of examination.

Sufficient, perhaps, has been said to develop the nature of the obstacles which the process of putrefaction is likely to offer to the employment of the Docimasia Pulmonaris, as well as to point out the means by which those obstacles may be removed. But, as there is still a collateral proof, which lies open to the medical witness, it will be necessary to determine how far, in the absence of all other evidence, he is justified in relying on this. I allude to the test of PLOUCQUET.

In order to understand the nature of this test, we must bear in mind the changes which take place in the lungs by the establishment of the process of respiration. Previous to birth, the pulmonary vessels circulate but a very small quantity of blood through the respiratory organs, the greater portion of the contents of the right ventricle passing directly through the canalis arteriosus into the aorta.* Now, in consequence of the great quantity of air introduced into the air cells of the lungs by the act of respiration, and in consequence of the greater buoyancy which these organs thereby acquire, we are apt to form an erroneous judgment respecting the change which really takes place; we are apt to conceive that they become of less specific gravity than they were originally. So far from this being the case, however, their weight becomes nearly doubled; and this increase of weight they derive from the circumstance of a much larger quantity of blood becoming circulated through them. The increased buoyancy, therefore, is owing to a simple mechanical cause, to the retention of a vast quantity of air in their retiform structure; and so well distributed is this air, that it is enabled to counteract the increase of weight which is brought about by the alteration in the course of the circulation.

The test recommended by Ploucquet is founded on these simple principles. We are to determine the weight of the body of the child, then to remove the lungs from the chest, and, having weighed them, to ascertain what proportion the weight of the lungs bears to the weight of the body. Whatever that proportion may be, it is clear, from what has been above stated, that it will be nearly twice as great in fætuses which have respired as it is in those which are still-born. Of course, it was necessary that some standard should be fixed by which the result, in either case, might be compared; and accordingly Ploucquet performed some experiments on the subject, and from these he deduced the following proportions: 1st. That where respiration had not taken place, the weight of the lungs was, to the weight of the body, in the ratio of 1 to 70. 2d, That where the act of respiration had been completely performed, the weight of the lungs was to the weight of the body in the ratio of 1 to 35.7

It has been objected to these inferences of Ploucquet's, that his experiments were not sufficiently numerous, and that the average was fixed as much too high in the one case as it was

Professor Foderé and others have looked upon the presence of blood in the pulmonary vessels as affording most certain evidence that respiration has taken place, and its absence they have regarded as tending to prove the contrary. Of four stillborn subjects, which I have successively examined, I have found semi-coagulated blood in the pulmonary vessels; and in several, in which respiration bad taken place, none was found, owing to accidental causes. This will suffice to show how little reliance is to be placed upon such an appearance.

+ The weight of the air introduced into the lungs by the process of respiration cannot be considered as adding to the absolute weight of these organs, since they are weighed in air.

407. No. 79, New Series.

7

too low in the other. It has certainly been proved by the observations of several distinguished physiologists, since his time, that his data were not well founded. Professors Schmitt, of Vienna, and Chaussier, of Paris, in order to investigate the truth of his positions, undertook a series of experiments on the subject, and the results at which they arrived are, that the body of a fætus which has respired has rarely so low a ratio as 50 to 1, taken with the lungs; while the body of a foetus which has not respired generally bears a lower ratio to the weight of the lungs than as 35 to 1.*

During the last summer, I employed this test in four cases on stillborn subjects, and the proportions which I obtained will be seen below.

Weight of the Lungs. Weight of the Body. Proportion.
Grs. 640

Grs. 38,400 1 to 60
687

33,847 1 to 53 300

14,400 1 to 48 1950

41,760 1 to 21. It will be observed, that the three first of these cases correspond very nearly with that proportion which previous calculations had given; but the last is to be regarded as a most extraordinary exception to the rule. The weight of the body of this fætus was about the common average; and, therefore, the extreme preponderance is to be set down to the lungs; for it will be seen by the table that they were three times the weight of those organs in the two first cases, and six times the weight of those in No. 3. In fact, their enormous size did not fail to strike every observer, and, from their appearance, it was at once concluded that they would bear a considerable proportion to the weight of the body. Such instances, however, of so great a departure from the standard, are to be looked upon as extremely rare, and as altogether insufficient to invalidate the general application of the test.

It cannot be denied that the body of the fætus is liable to vary in weight, according to the greater or less quantity of adipose substance about it, as also according to its length and its sex: but these variations are confined within a small limit, and the knowledge of the causes from which they may proceed will be sufficient to remove the errors that might otherwise possibly creep into the calculation. It is also worthy of note, that the ratio is exceedingly constant with regard to the fætus in utero up to the full period of gestation, which shews that there is certainly a strict relation between

* For the tables which these physiologists have drawn up relative to this subject, vide Orfila, Traité de Médecine Légale, tome i. p. 348.

the development of parts; and if it be not always discovered after the establishment of the respiratory process, we must endeavour to make allowances for its absence, and frame our decisions accordingly.

Now, by applying the test of Ploucquet to the cases which we have been considering, we shall, in a great majority of instances, be able to corroborate the presumption which we may have drawn from other facts. Supposing, in either of the cases in which putrefaction has taken place, that we find the weight of the lungs to be, to the weight of the body, in the ratio of about 1 to 50, we are certainly confirmed in our suspicion that respiration had not been performed; for the air generated by putrefaction cannot give to these organs any additional weight. This, as I have already stated, must be derived solely from the altered course of the circulation. But, it may be argued, the ratio may turn out to be higher than 1 to 50; it may be, for example, from 1 to 30 or 40, and thus closely approximate to the results obtained by the experiments on fætuses which have respired. This, it is true, is converting the exception into the rule; but, nevertheless, it shall be admitted, for the sake of argument, that a higher ratio is obtained than that which I have above given. What, therefore, is to be the course which the medical jurist ought to pursue in this dilemma? He has, I conceive, simply to consider on which side the error may probably lie, or whether both results may not be reconciled without any great violation of fact or reasoning. In the cases which I have supposed, the latter plan may be safely followed, since a high ratio, obtained by the test of Ploucquet, may by possibility occur in a fætus which has not respired, as well as in one which has respired; and, although a low ratio might be strongly corroborative of our original presumptions, a high ratio would not militate against it.

Therefore, if, in the examination of a child suspected to have been born alive, we find that the lungs will float when immersed in water, but that they may be deprived of their buoyancy by moderate compression; as also that the air to which that buoyancy is owing is confined to the surface in the form of large vesicles, and not diffused uniformly throughout the cellular parenchyma of the organs: it will matter but little whether their weight be, to that of the body, in the ratio of 1 to 50 or of 1 to 35. In either case, the practitioner will be justified in affirming that the suspicion of the child having respired is unfounded. If he obtain the lower ratio, it will be so far confirmatory of the correctness of his decision, as it corresponds with the general rule; if the higher,

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