The Interpretation of Mendelian Phenomena

Abstract

I AM sorry Mr. Lock should mistake what I devoutly hope is a sense of proportion for a desire to belittle Mendelian work. In science clear ideas are of importance, and I wished to elicit something more definite than the vague notion that Mendelism will someday and somehow furnish a master key to the problems of heredity. I made no complaint that Mendelism “does not immediately lead to the solution of all the most difficult problems which biology affords,” as Mr. Lock rather extravagantly asserts, but merely asked what conceivable bearing it can have on any problem save that of sex. By the problem of sex I mean the problem of the function of sex—or of conjugation if Mr. Lock prefers. I confess I cannot imagine what light Mendelism has shed on the question of the alleged transmission of acquirements, and as for the “problems of the actual transmission of characters,” these, as dealt with by Mendelians, are nothing other than problems of sex. That is, Mendelian experiments demonstrate nothing more than the degree in which certain characters (mutations) are transmitted or distributed under, or affected by, conditions of conjugation. Doubtless it is true that the majority of Mendelian cases have been observed in self-fertilised types, but I am not aware that they have ever been observed unless cross-fertilisation had previously occurred. In parthenogenesis the individual arises from an unfertilised ovum; how, then, is segregation possible? What segregates?