We find at this early stage oedema of the part.
Where the dropsical condition is more or less general the term " anasarca " is applied to it; if the tissues are infiltrated locally the term " oedema " is employed; and various names are applied, with a local significance, to dropsies of individual parts or cavities, such as " hydrothorax," " hydroperitoneum " or " ascites," " hydrocephalus," and so on.
It is invariably the result of some cause acting generally, such as renal disease, valvular defect of the heart, or an impoverished state of the blood; while a mere oedema is usually dependent upon some local obstruction to the return of blood or lymph, or of both, the presence of parasites within the tissue, such as the filaria sanguinis hominis or trichina spiralis, or the poisonous bites of insects.
Welch produced oedema of the lungs experimentally by increasing the pressure in the pulmonary vessels by ligature of the aorta and its branches, but this raised the blood pressure only about one-tenth of an atmosphere, while in some of Loeb's experiments the osmotic pressure, due to retained metabolic products, was equal to over thirty atmospheres.
Thus differences in osmotic pressure may be much more powerful in producing oedema than mere differences in blood pressure.
Widal, Lemierre and other French observers have noted a diminution in the excretion of chlorides in nephritis associated with oedema; Widal and Javal found that a chloride-free diet caused diminution in the oedema and a chloride containing diet an increase of oedema.
Some other observers, however, have not got such good results with a chloride-free diet, and Marishler, Scheel, Limbecx, Dreser and others, dispute Widal's hypothesis of a retention of chlorides as being the cause of oedema, in the case of renal dropsy at all events; they assert that the chlorides are held back in order to keep the osmotic pressure of the fluid, which they assume to have been effused, equal to that of the blood and tissues.
Bainbridge suggests that a retention of metabolic products may cause the oedema in renal disease, Bradford having previously shown that loss of a certain amount of renal tissue caused retention of metabolic products in the tissues.
The local oedema seen in some nervous affections might be explained on the hypothesis of increased metabolic activity in these areas due to some local nervous stimulation.
1356; Salvioli, " Production of Oedema," Virchow and Hirsch's Jahresbericht (1885), i.
Trans., Oxford, 1891); also, The Germ Plasm (London, 1893); Welch, " Oedema of Lung," Arch.
The physical signs are those of broncho-pneumonia; oedema of the lungs soon supervenes, and death occurs in three or four days.
There is general engorgement and oedema of the lungs, with pneumonic patches varying in size and irregularly distributed.
They are enlarged to the size of an almond, rounded, firm and pink; there is some engorgement and oedema on section; the substance is rather soft, and can be scraped off with a knife.
It is probable that the kidneys also have an internal secretion, and that the great oedema sometimes found in kidney disease is rather due to the action of some proteid body resembling in its effects the streptococcus anti-toxin, than to accumulation of water due to imperfect action of the kidney.
Thus, to mention examples, diphtheria toxin produces inflammatory oedema which may be followed by necrosis; dead tubercle bacilli give rise to a tubercle-like nodule, &c. Furthermore, a bacillus may give rise to more than one toxic body, either as stages in one process of change or as distinct products.