In Zygosaccharomyces described by Barker (1901) we have a form of the usual sprouting type, but here again there is a fusion of two cells to form a sporangium.
In Schizosaccharomyces and Zygosaccharomyces, however, we have a fusion of nuclei in connexion with the conjugation of cells which precedes sporangium-formation.
The theory may be put forward that the ordinary forms have been derived from sexual forms like Schizosaccharomyces and Zygosaccharomyces by a loss of sexuality, the sporangium being formed parthenogenetically without any nuclear fusion.
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