A new aspect of the life cycle ofCandida tropicalis

The life cycle ofCandida tropicalis has been elucidated by nuclear staining. We were able to distinguish 5 stages: (1) the sexually active unstable haplophase which either can mutate directly to (2) the sexually inactive haplophase, or is converted to (3) the diplophase by “autoploidization”. The unstable diplophase changes into the sexually inactive haplophase, which is stable, by “budding meiosis’. Chlamydospores (4), which are possibly formed by sexually inactive haploid cells, are true resting spores, and during their germination only mitosis takes place. The buds formed during germination may develop into either the sexually active, or the inactive haplophase. During budding meiosis in the diplophase, multinucleate giant cells (5) may occur. The authors do not consider the latter to be metabasidia. Instead, they might in some way be homologus with asci, and their daughter nuclei might be comparable with the nuclei of ascospore initials. These new nuclei migrate successively into new buds which process results in a short chain of haploid cells. True ascospores have not been found. From these findings it is likely thatC. tropicalis is closely related to the ascomycetes rather than to the Hemibasidiomycetes.