INTRODUCTION Fungi and Human Disease.—The first pathologic conditions ever shown to be caused by microbes in man, namely, thrush,1favus,2and ringworm,3were all fungus diseases. Notwithstanding this, the pioneer workers in medical microbiology centered their attention primarily and for many years on the pathogenic bacteria because these organisms, as a rule, are more aggressive than the fungi and they take a heavier toll on human life. In the course of time, however, a large proportion of the major problems created by the infecting bacteria have found satisfactory solution, and now the interest of microbiologists is being gradually moved toward the fungus infections. Many medical centers throughout the world have already organized well-equipped laboratories dedicated to research in this new field; the biology of the pathogenic fungi is being carefully studied, and during the last decades several hitherto unknown mycoses have