Dr. A. discovers a further evidence of the relation which dropsy bears to diseases of local excitement, in the effects it produces on the general system. Thus, during the continued effusion of serum in anasarca, there is sometimes a large quantity absorbed and carried out of the body; by which a regular draught is made upon the nutrient principles of the blood, which must naturally create effects like those arising from the continued discharge of pus from a suppurating surface. In both cases the local disease, when extensive and of long duration, will necessarily occasion an exhaustion of the vital powers, by which that condition of the system termed cachexy will be induced. "The exhausted or cachectical state, therefore, of the system, which has been so variously accounted for, and so frequently assigned as a principal cause of both local and general dropsy, is a direct consequence of the agency of some power diminishing the vital strength at its source; and in the case of a chronic and long continued serous inflammation, it will proceed from the daily abduction from the circulation of a portion of its vital fluid: and whether it be pus or serum that is drawn from the body; or whether it be from any permanent failure in the supplies of nutriment to it, the effect will be the same, as if a certain quantity of blood was daily abstracted from the system." Dr. A. continues to remark that, under these circumstances, a suppurating surface will readily become gangrenous, from any cause temporarily exciting it, and that, in like manner, a higher inflammation may sometimes supervene upon an oedematous limb, as in the former case, and terminate in gangrene. "Hence, therefore, the tendency of dropsical parts to fall into gangrene, and which has been urged, as an argument, in proof of debility being the cause of the serous effusion, is only what is common to other forms of local inflammation, under a similar condition of the body." From the view he has adopted of the nature of dropsy, Dr. AYRE thinks that the excitement of the parts, giving rise to the effusion, may be either 1st. Sub-acute or chronic. 2nd. Symptomatic or idiopathic. In other words, that it may arise from a local disease, or from the common causes of inflammation; and that these causes may be either general or particular. 3d. That the serous inflammation may be either local or general, giving rise to a general or local effusion.