It may be interesting, before we leave Mr. Spencer, to see whether he even now assigns to continued personality and memory the place assigned to it by Professor Hering and myself.  I will therefore give the concluding words of the letter to the Athenaeum already referred to, in which he tells us to stand aside.  He writes “I still hold that inheritance of functionally produced modifications is the chief factor throughout the higher stages of organic evolution, bodily as well as mental (see ‘Principles of Biology,’ i. 166), while I recognise the truth that throughout the lower stages survival of the fittest is the chief factor, and in the lowest the almost exclusive factor.”

This is the same confused and confusing utterance which Mr. Spencer has been giving us any time this thirty years.  According to him the fact that variations can be inherited and accumulated has less to do with the first development of organic life, than the fact that if a square organism happens to get into a square hole, it will live longer and more happily than a square organism which happens to get into a round one; he declares “the survival of the fittest”—­and this is nothing but the fact that those who “fit” best into their surroundings will live longest and most comfortably—­to have more to do with the development of the amoeba into, we will say, a mollusc than heredity itself.  True, “inheritance of functionally produced modifications” is allowed to be the chief factor throughout the “higher stages of organic evolution,” but it has very little to do in the lower; in these “the almost exclusive factor” is not heredity, or inheritance, but “survival of the fittest.”

Of course we know that Mr. Spencer does not believe this; of course, also, all who are fairly well up in the history of the development theory will see why Mr. Spencer has attempted to draw this distinction between the “factors” of the development of the higher and lower forms of life; but no matter how or why Mr. Spencer has been led to say what he has, he has no business to have said it.  What can we think of a writer who, after so many years of writing upon his subject, in a passage in which he should make his meaning doubly clear, inasmuch as he is claiming ground taken by other writers, declares that though hereditary use and disuse, or, to use his own words, “the inheritance of functionally produced modifications,” is indeed very important in connection with the development of the higher forms of life, yet heredity itself has little or nothing to do with that of the lower?  Variations, whether produced functionally or not, can only be perpetuated and accumulated because they can be inherited;—­and this applies just as much to the lower as to the higher forms of life; the question which Professor Hering and I have tried to answer is, “How comes it that anything can be inherited at all?  In virtue of what power is it that offspring can repeat and improve upon the performances of their parents?”