the sternum, between the eighth and ninth ribs, and out close to the spine. Four ounces of blood escaped by anterior wound. Respiratory murmur equally inaudible on both sides. On the 23rd February, the dog ate and drank, and was very lively. Respiratory murmur audible on both sides.

1st March. Has remained healthy, and showed no sign whatever of having been wounded. Destroyed by half a drachm of prussic acid.

Upon examination, the wound of entrance was not visible; the wound of exit was visible from within, and was about two inches in length. Both lungs collapsed on raising the sternum.

No effusion in either pleuritic cavity.

Right lung bound posteriorly to the walls of the thorax, the posterior mediastinum, and the diaphragm.

These adhesions were carefully detached, and the lungs and heart taken out. The right lung was felt to possess the normal vesicular crepitation upon pressure. Upon its upper and middle lobe were three separate patches of highly congested lymph, about an inch in diameter; each patch joined to its fellow by a bridle or narrow band also of highly congested lymph. It was doubtful whether the wound of exit was not more or less plugged up by this effused lymph. The place of these deposits corresponded with the points of adhesions previously mentioned. The nozzle of a pair of bellows was firmly inserted in the trachea, and upon using the bellows both lungs became fully inflated, and, taking care to effectually compress the trachea, they remained so after ceasing the inflation. It was certain that there was no escape of air by the wound. The patches of lymph were now carefully dissected off, and a most careful examination made, but no injury to the lung was seen. On cutting into its substance, every part was found healthy.

Erperiment 5. On the 1st of March, shot a dog with a minié bullet, through the right side. He remained alive until the morning of the 4th, without apparent suffering. Upon examination, the bullet was found to hare entered at, and fractured the fifth rib, skirted, without having actually wounded upper and middle lobe of right lung; bruised, but not entered pericardium, and passed out at second left rib, close to sternum, and was found within the skin close to middle of humerus. Upon examination, there were seen several recent pleuritic adhesions, and some of these adhesions had partially closed the wound of entrance in right pleural caritr. Several marginal portions of upper and middle lobes of right lung were condensed into a black mass resembling the congestion caused by a bruise. On being cut into, the surfaces were moist, and no appearance of lymph. These dark portions sank in water, and were not, by pressure, made to float The left pleural carity was found filled with bloody serum, and had not been entered by the ball No signs

of pleuritis in this cavity. Both lungs remained fully distended after artificial inflation, and when the trachea was tied, did not collapse under pressure. Heart filled with fibrinous clots and dark coloured grumous blood.

Dr. Houston, in the ninth volume of the Philosophical Transactions, page 138, gives the following experiment; both sides of the thorax were opened in two puppies, “ so as,” he adds, “ to discover the lungs on each side, but which did not however subside, but rather seemed to thrust themselves outwards.” Dr. Van Swieten performed the following experiment, as related in the same Transactions, page 139: “ A middle sized dog was tied to a board, and his thorax was opened on both sides, with a large wound. His voice did not fail, and the lungs were so far from collapsing, that a lobule of them thrust itself through each aperture.”

The following experiments, Nos. 6 and 7, corroborates the foregoing statements. The right pleural cavity of a healthy dog was carefully opened, so as to avoid wounding the lung; the same phenomena were witnessed as in No. 3, viz., air passing in on inspiration, and out on expiration. After death, having removed the whole anterior wall of the thorax, the lungs were fully exposed; upon artificially inflating the left lung, and then strongly compressing the trachea, the right lung having previously collapsed ; and then pressing so as to empty the inflated lung, the air

passed rapidly by the bronchial communications into the other lung, and fully inflated it.

Experiment 7. On the morning of the 1st of February, 1858, a healthy dog was put into a properly adapted case, with a glass slide, and placed under the influence of “ puff-ball.” A portion of the fifth right rib was then dissected out, sufficiently large to bring the lung into view, having carefully avoided wounding it. The lung was then distinctly seen to contract upon inspiration, and to expand upon expiration.

Various writers have offered explanations of this curious phenomenon. Dr. Hales, in his Statical Essays, page 74, in writing upon this point, would lead us to infer that he considers this expansion of the lung to proceed, when there is an opening on one side only, from the force of the blood, in the pulmonary circulation, dilating the lung.

Dr. Hoadley, in his Three Lectures on the Organs of Respiration, in 1737, when reasoning upon the experiments of Dr. Houston, explains the phenomenon as follows:-“In expiration, the air in the unwounded side was condensed, and part of it, instead of going out at the windpipe, forced its way into the lung of the wounded side, and dilated it, till the air within it came into an equilibrium with the external air which surrounded it; and in inspiration, when the air in the lung of the unwounded side became rarer than the external air, the lung in the wounded side was compressed, and

part of the air within it was, by the pressure of the external air, forced back into the lung of the unwounded side, till the equilibrium was again restored.”

From the foregoing, we may infer that Dr. Hoadley considered the action of the lung, after an opening into the thoracic cavity, to be owing to the varying elasticity of the air within that cavity.

An explanation is also given by Dr. Halliday, in his Observations on Emphysema. He says,“Should, however, the patient, in making an effort to expire, contract the glottis, the air contained in the lung of the sound side, meeting with no resistance, will, by the communication of the branches of the trachea, expand the lung of the wounded side, so as to cause it to protrude at the wound.”

The above explanation by Dr. Halliday appears to me to be the best and most simple; and perhaps a more acute observation, if it were wholly true, was never penned in the form of a physiological explanation of a practical fact. But, nevertheless, it does not explain the whole case, for it requires a “contraction of the glottis.” Now the phenomenon in question constantly happens when there is no contraction of the glottis.

If it be granted that the lung may be wounded, and yet appear uncollapsed, -I say appear uncollapsed, because the inflation is not the effect of natural respiration, but the consequence of a spasmodic closure of the glottis at the moment of