The two theories of uremia that claim most attention at the present time are the toxemic and what may be called terminal state—the idea that this condition is not a pathological unity at all but a final dissolution. The latter conception is founded more on the failures of research to elucidate a specific etiological factor than on the lack of a clear-cut clinical picture. Since this idea cannot be tested by investigation, it demands no special consideration. The hypothesis that uremia is a toxic state, however, has much in its favor by way of analogy, and has become more or less rooted in our minds because of the men who have sanctioned this theory in one form or another.
As to the nature of the toxic agent, the ideas advanced may be subdivided under two heads, depending on whether the toxic material is supposed to be a