GENETICS OF NATURAL VARIANTS. VI : SOME ABNORMAL SPORES OF ISOETES PANTII GOSWAMI AND ARYA RESEMBLE FOSSIL LYCOPODS

This paper describes rare and unusual spores found in the heterosporous sporangia of Isoetes pantii which are comparable with the fossil spore genus Nathorstisporites belonging to the cone genus Lycostrobus. Lepidodendralean ancestry of the living genus is further strengthened by this demonstration of an "evolutionary reversal.” The production of these “ancestral spores” is discussed in the light of new emerging fact of evolution of X-chromosomal mechanism, probably the first in any pteridophyte.