(21.6. 195 ) (With plates II to VIII) Mycologists in general still assume that the life cycle of the fungus Coccidioides immitis possesses two distinct phases: 1) a cultural phase, represented by a mold-like, hyphomycetic form, and 2) a tissue phase, characterized exclusively by the "spherules" (sPorangia, ascus, ascocarp). Furthermore, it is implicitly assumed that spherules cannot be produced outside of the infected animal tissues, while mycelia do not form in the living tissues. Many findings which are contrary to these hypotheses have accumulated during the last two decades. However, the reports are so scattered that a review of these valuable but buried facts seems appropriate at this time.