The mortality of croupous pneumonia is greater than that of any other acute disease; higher than that of diphtheria, and next below that of tuberculosis. The mortality statistics in private and hospital practice show a percentage of from twenty to forty. The census of 1890 indicated that 76,496 persons died of pneumonia in the United States during the preceding year, a deathrate of 186.94 per 100,000 of population. The census reports of 1870, 1880 and 1890 show that the deaths from this disease have slightly increased. It is the most wide-spread of all acute diseases.
It is nearly twenty years since Fränkel discovered the diplococcus lanceolatus and established its causative relation to croupous pneumonia, since which time renewed efforts have been, and are being, made for the discovery of a specific prophylactic and curative agent. Some years ago the Klemperers demonstrated that the injection of blood-serum, obtained from one who