Chapter 15

PRELIMINARY REMARKS. FIRST PART:--THE FACTS TO BE CONNECTED UNDER A SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF REPRODUCTION--REGROWTH OF AMPUTATED PARTS--GRAFT-HYBRIDS --THE DIRECT ACTION OF THE MALE ELEMENT ON THE FEMALE--DEVELOPMENT--THE FUNCTIONAL INDEPENDENCE OF THE UNITS OF THE BODY--VARIABILITY--INHERITANCE-- REVERSION. SECOND PART:--STATEMENT OF THE HYPOTHESIS--HOW FAR THE NECESSARY ASSUMPTIONS ARE IMPROBABLE--EXPLANATION BY AID OF THE HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN THE FIRST PART--CONCLUSION.