During the past few years many new methods for the treatment of that very fatal disease of infancy, pneumonia, have been instituted, but few of these have been markedly successful. Many of us believe that the use of out-of-door air has done more to limit the mortality of pneumonia than has been demonstrated for any of the treatments based on laboratory investigation.
Of the three treatments that come under this class one may mention the use of leukocyte extracts advocated by Dr. Hiss; the use of vaccines either commercial or autogenous, and, finally, the use of the serum.
The leukocyte extract of Hiss has produced some striking results, but has not as yet had sufficient use, I believe, to determine accurately its value. But in a report issued by Hiss and Zinsser1 in 1908, they describe eight cases with recovery and with a reduction of temperature usually within two