The cause of this phœnomenon can easily be explained. If an obstruction exist in either side of the heart, or in the lungs, the blood to be poured into the right auricle, from the vena cava inferior, must be obstructed, its flow into that vessel from the liver will be equally checked, the thin coats of the hepatic veins and of the branches of the vena porta will yield and distend the soft substance of the liver. Hence are caused the discharges of blood from the hæmorrhoidal veins, which form one of the characteristic symptoms of the disease; for as these vessels empty their blood into the meseraic veins, which open into the vena porta, if the meseraic veins be obstructed, the hæmorrhoidals must consequently be also affected, and they easily burst open from too great distention. The hæmoptoe, which also is so frequent, is as easily explained on the same principle. The cause of the serous collections is not so readily discovered. In this case, as in most of the others, we found a considerable quantity of water in the abdominal cavity. Dropsy is commonly considered as a disease of debility, but in these cases it often appeared, while the strength was unimpaired, and the heart acted with very extraordinary force. If the blood was driven with rapidity through the arteries, while an obstruction existed at the termination of the venous system in the heart, the consequences must have been accumulation in the venous system, difficult transmission of the blood from the extreme arteries to the veins, overcharge of the arterial capillary system, consequent excitement of the exhalant system to carry off the serous part of the blood, for which it is adapted, and thence a serous discharge into the cavities, and also on the surface of the body; for great disposition to sweating is a common symptom. In addition to these, there is another cause of the universality of these effusions. The blood, in all the cases which I have examined, is both before and after death, more thin and watery than healthy blood. How this happens, our knowledge of the theory of sanguification does not enable us to determine. Perhaps, as the imperfect respiration must cause a deficiency of air, and consequently of oxygen, in the lungs; and as the absorption of oxygen is a cause of solidity in many bodies, this tenuity of the blood may proceed from a deficient absorption of oxygen. However this may be, it is certain that the blood is very much attenuated, though with considerable variations in degree, as it is sometimes found thin on opening a vein, and at a subsequent period is thicker; varying perhaps according to the continuance of ease or difficulty in respiration. It is certain, that this attenuation of the blood must tend to an increase of the serous exhalations.