SUMMARYPrincipal points in defense of a protosexual cycle in yeasts, as related to Dr. El-Ani's criticisms, are the following:1.The term protosexuality serves a useful purpose for designating a sexual cycle without sexual spores, as currently known for strongly heterothallic yeasts.2.Direct examination for protosexuality inChlamydozyma,is simple and dependable if freshly isolated, highly active cultures are used.3.The active bisexual cells, which are formed after the union of heterothallic gametes, are uninucleate and, therefore, should be capable of recombination if meiosis occurs, as it is presumed to do. Initially pure cultures of active bisexual cells may, within the course of a few days, yield more than 90% of unisexual cells. None are ascospores; they develop as vegetative cells.4.If, as Dr. El-Ani contends, these yeasts are basically ascosporogenous but possess a genetic block to sporulation, the complete blocking of sporulation in this genus should entirely block the formation of viable unisexual cells from bisexual cells. However, unisexual cells are produced in abundance.5.Perhaps the genetic information most needed to begin to understand sexuality in protosexual yeasts is the elucidation of nuclear reactions involved in the change from bisexual cells to unisexual cells.