Note 60 — APPENDIX A. Mr. Gulick's Criticism of Mr. Wallace's Views on Physiological Selection.
Reading edition
"Positive segregation" is Mr. Gulick's term for forms of homogamy other than that which is due to selective fertility. Of these other, or "positive" forms, natural selection is one; but as it is far from being the only one, the criticism points out that utility is not the only conserving principle with which selective fertility may be associated.