Note 33 — Part I. ON THE SEASONAL DIMORPHISM OF BUTTERFLIES.

I at first thought of designating the two forms of cyclical or homochronic heredity as ontogenetic- and phyletic-cyclical heredity. The former would certainly be correct; the latter would be also applicable to alternation of generation (in which actually two or more phyletic stages alternate with each other) but not to all those cases which I attribute to heterogenesis, in which, as with seasonal dimorphism, a series of generations of the same phyletic stage constitute the point of departure.