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 title paper in this compilation, "Filtrable Bacteria," was published in the Journal of Infectious Diseases in 1931. This was the third in a series dealing with the subject of bacterial variability. The first ("Microbic Dissociation") was published in 1927, and the second ("The Twort-d'Herelle Phenomenon") in 1928. "Filtrable Bacteria" continues the study of dissociative variations among bacteria, and addresses the method of production, the cultural behavior, the morphology and the filterability of what may be termed "the filterable virus stage" of the Shiga dysentery bacillus. PHILIP HADLEY This present compilation also incorporates a 1937 article, "Further Advances in the Study of Microbic Dissociation."

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

Frank Billings' classic and forever relevant 1916 masterpiece, with a 2013 Foreword by S. H. Shakman of the Institute Of Science (www.InstituteOfScience.com) "Four Score and Seventeen Years Ago," providing an historical review and update on the subject of the relation between oral infections and systemic diseases.

A review and compilation of key works on the relation between dental infections and mental illnesses, with an introduction and overview of the definitive bacteriological work of E.C Rosenow of the Mayo Foundation, by S. H. Shakman, and incorporating the foundational historical works by Henry Upson and Henry Cotton.