A brief history of the lysigenous gland hypothesis

This paper summarizes the early history of the lysigenous gland concept, traces its evolution to recent times, and explores some possible causes of conflicting reports of lysigeny and schizogeny. Secretory cavities and ducts are generally thought to form either through the schizogenous separation of cells or through lysigeny (cell lysis). Gland lysigeny was first proposed in 1857 by Karsten, who believed that plant tissues represent solidifications of humoral fluids and that plant secretions are formed by the resorption of previously solidified cells. The lysigenous gland concept has modernized as our understanding of cytology has improved, but it was established early, from Karsten's hypothesis, long before the influence of artifacts of specimen preparation was appreciated. Different methods of specimen preparation, including variations in the mounting media used to mount freehand sections, may have caused some of the discrepancies between the findings of lysigenists and schizogenists. Tschirch and Haberlandt promoted the schizolysigeny concept, and believed that the conflicting reports resulted from incomplete observations of a developmental process that included both schizogenous separation of cells and cell lysis to form secretory cavities and ducts. Both lysigeny and schizogeny have been reported in the recent literature, although most reports of lysigeny have been opposed by conflicting observations of schizogeny, and lysigeny may represent a false category of gland development caused by the misinterpretation of artifacts.