Theoretical Discussion. The starting point of the preceding studies was the observation that antigen and antibody had been found to coexist in reactive form in the body. Eisenberg's observation seemed to furnish a striking analogy to this phenomenon in the test-tube. With the changed interpretation of this observation, its value as an analogy disappears. Hence, it again becomes of interest to inquire whether the studies on equilibrium in precipitation have shed any further light on the problem of coexistence of antigen and antibody in the body.

If the preceding data be analyzed, it is evident in the first place that in the form of precipitate antigen and antibody can coexist as independently demonstrable entities, although in combination. Coexistence in such a state, namely, as precipitate, is, of course, hardly comparable with coexistence in the blood, or within the cells. It has been shown that in solution precipitin and precipitinogen cannot coexist without undergoing combination and precipitation.

This content is only available via PDF.