The most serious epidemic of psittacosis thus far recorded occurred last winter. The number of cases reported between July and February throughout the world reached nearly four hundred, and undoubtedly many cases occurred that were not reported. The mortality among these patients was about 35 per cent. The countries in which cases are known to have occurred included the United States, England, Germany, France, Austria, Denmark, Switzerland, Netherlands, Czechoslovakia, Argentina, Brazil, Paraguay and the Hawaiian Islands. The reaction of the public to these scattered outbreaks was unusual. Since the epidemiology of psittacosis is now clearly understood, an occasion cannot arise in which the disease is beyond control. The public should be assured, therefore, that a great epidemic would be impossible. In an elaborate review prepared for the League of Nations,1 Rouvakine shows that psittacosis has appeared in medical reports for at least fifty years. Hymann reviewed the literature up