pathic sthenic inflammation of the lungs, such as exposure to cold, wet, &c., there are a set of causes that peculiarly dispose to the occurrence of this disease, after surgical operations and injuries. These are divisible into two classes, both of which, however, must concur for the production of the variety of the disease now under consideration.

1st. In the first class are comprised those causes that act mechanically, by giving rise to a congestive condition of the posterior part of the lungs, as the recumbent position long continued.

2nd. In the second class, those that act by diminishing the functional activity of the nervous system, as profuse suppuration, long confinement in hospitals, and irritative fevers, more particularly when assuming a typhoid type, and when occurring in individuals advanced in life.

Age may also perhaps exercise some little influence on the production of congestive Pneumonia, which would probably be more marked than it is, were it possible to separate the few cases of sthenic from those of the congestive form of the disease. On taking, however, the aggregate of the two varieties of Pneumonia, it will be found that the average age of the patients in whom inflammation of the lungs was found, was . 44.2 years.

Of the doubtful cases

Of the cases in which no inflammation or congestion of those organs occurred

.39.4

So that the average difference in age between those

cases in which Pneumonia occurred, and those in which it did not, amounted to 8.3 years.

That the recumbent position, even when long continued, is not of itself sufficient, in an otherwise healthy person, to give rise to a congested state of the posterior part of the lungs, is evident, as we do not find this effect produced in those who preserve this posture, as in some modes of treatment for spinal distortion, for months, and even years. It is, therefore, necessary that the depressing causes of disease that have already been enumerated should co-operate with it, in order to give rise to congestion, even in so vascular and spongy an organ as the lung; and this we find to be the case. If we take the period that the patients mentioned in the Table lived in the hospital, as equivalent to the time that they maintained the recumbent posture, which, from the nature of the operations and injuries under which they suffered, in most of the cases, we are justified in doing, we shall find, as will immediately be shown, that those who died of Pneumonia preserved this position, on an average, for a much longer period than any others, except the phthisical patients.

Although the circumstances that have just been mentioned tend, to a certain degree, to expose the patient to the occurrence of congestive Pneumonia, yet, without doubt, the most active agent in the production of this disease is a diminution in the functional activity of the nervous system, whether this be the consequence of the irritation of opera

tions and injuries, of long-continued and profuse discharges, or of confinement in the comparatively impure air of hospitals,—all of which depressing influences are, in most cases, in action at the same time. That these circumstances operate in predisposing to the occurrence of the disease under consideration, may be seen by examining the Table appended to this paper, by which it will be found that all those who died of this affection had been the subjects of such operations or injuries as are necessarily followed, either by much irritative fever, or by very profuse and wasting suppuration; whereas those in whom the lungs were found healthy, died, with but one exception, before there was time either for suppuration to have taken place or for irritative fever to have been set up.

That a long residence in a hospital, in conjunction with other depressing causes of disease, and the maintenance of the recumbent position, will tend to dispose to the occurrence of congestive inflammation of the lungs, may be seen by the annexed Table,* on examining which it will be found that of the twenty-eight cases of Pneumonia, only one died before the fourth day; whereas, of the thirteen cases in which the lungs were found healthy, no less than eleven died before that period-before, indeed, any inflammatory condition of these organs

* In the second class of cases, a note of the length of time the patients lived in hospital was kept only in ten, and in the fourth class in thirteen cases, instead of in eleven and fourteen respectively.

could be expected to have manifested itself; and of these eleven, no less than eight died on the first day, or, in fact, were brought to the hospital moribund. Of the remaining two cases, one died on the fifth day, and the other on the forty-fourth day, after being operated upon for strangulated inguinal hernia, a remarkable exception to the rest of the series.

The average time, then, that the patients lived after admission into the hospital was as follows:Cases in which the lungs were inflamed. 20-7 days. Doubtful cases

12.3

Cases in which the lungs were found diseased, but not inflamed

22.7

Cases in which the lungs were healthy. 16

The reason of the high average of the time that those patients lived in whom the lungs were found diseased, but not inflamed, is, that of ten in that class, three died of phthisis on the thirtieth, fiftyfourth, and seventieth day respectively, after admission into the hospital. If these cases are excepted, we shall find that the remainder lived, on an average, only 8.4 days.

It would be occupying too much of the Society's time, were I to enter, at any length, upon a rationale of the operation of those causes that occasion a congested state of the lungs by lowering the energies of the nervous system. It can, however, easily be understood how the lungs, having once become engorged, a degree of inflammatory action, which, from the condition of the patient, must necessarily be of a low type, may be set up in an organ already disposed to its occurrence by the existence of an anormal quantity of blood in its vessels, more particularly in patients who have been rendered highly irritable by traumatic fever and profuse discharges.

The occurrence of congestive Pneumonia in a patient already suffering from the depressing effects of a severe injury or operation, is, of course, a complication greatly to be dreaded, and one which it has been shown is much more frequent than is usually believed. It is a complication against which it is necessary to guard as strictly as possible, both on account of the extreme danger that usually attends it, as well as on account of the disease assuming, in many instances, a latent character, the rational symptoms