All plants have alternation of generations
between a haploid spore-producing (sporophyte) stage and a gamete-producing (gametophyte) stage.
One question, left unanswered by Hofmeister, was how the alternation of generations of the 'higher cryptogams' or archegoniates related to the life histories of 'lower cryptogams' or thallophytes.
The ensuing debate focused on the origin of the asexual generation of land plants (i.e., the sporophyte) and is conventionally characterized as a conflict between theories of antithetic and homologous alternation of generations. This debate initially took place in the context of a common belief in the direct inheritance of form.
Celakovsky's (1874) purpose was to present an accurate classification of the alternation of generations (Generationswechsel).
Pringsheim (1876b) presented a contrary interpretation of the connection between alternation of generations in thallophytes and mosses.
Since, in evolution, the development of sex surely preceded alternation of generations, the gametophyte generation is considered, necessarily, to be older than the sporophyte generation (cf.
Brown (1935: 657-658) clearly believed, however, that "it is doubtful if any alternation of generations ...
Various arguments, based on evidence (real or supposed), have been laid down in favor of either the homologous theory or the antithetic theory of alternation of generations; that is, of land-plant sporophyte origins.