Dr. Andrew H. Smith of New York, in a recent paper1 with the above title, read before the Association of American Physicians in May, states that it is very likely that in ordinary pneumonia there must be infection with succeeding generations of microbes. Welch and others have shown that the virulence of the micrococcus lanceolatus is greatest when the coccus is youngest; that the most virulent microbes come from the edges of the consolidation. When the local process ceases to advance, it means that then young micro-organisms are no longer produced. This might be a reasonable explanation of the remarkable crisis in pneumonia, and yet the question arises, what share do the antitoxic products play in the result?
As long ago as 1888 Netter2 showed that mice and rabbits can be made immune to the micrococcus lanceolatus by injection of fluid from the dried spleens of infected animals.