In this work Philip Hadley provides a comprehensive discussion of the immense body of prior work on the occurrence of dissociation of bacterial forms, including much accomplished even prior to the start of the Twentieth Century. Hadley's work has apparently, unfortunately, not previously been published independently in book form, which may help explain why this exhaustive treatise has thus far evaded a more-deserved and widespread audience.

The working hypothesis ... is that the bacteriophage is either a definite stage in the cyclogeny of the bacterial species, or a functionally active particle accessory to one of these stages; and by the term "accessory" I mean possessing complementary or reciprocal biologic significance, such, for example, as the relation of sperm cell to ovum. With such a conception there is not any priority of significance in the relation between bacteriophagic corpuscle and the cell which it "attacks." Both elements are necesary components of a definite reproductive mechanism possessed by many, if not all, bacteria. This constitutes the nucleus of what I have termed my "homogamic theory" of bacteriophage action. PHILIP HADLEY