In this little book, Professor Trager has reviewed those relationships between different species of organism, usually referred to as mutualism. The importance of the subject is succinctly indicated in the first sentence of the first chapter: “No organism lives alone.” The book is written at a semitechnical level and can be comprehended readily by students in a general biology course.
As examples the author has chosen the best known mutualistic relationships. These include: cockroaches and bacteroids, leguminous plants and rhizobia, protozoans and bacteria, invertebrates and algae, higher plants and microorganisms, insects and microorganisms, various “hosts” and cellulose-digesting organisms, and microorganisms of the vertebrate gut. Also discussed are several behavioral associations, such as ants and aphids, the yucca and the yucca moth, certain “cleaning” relationships, and the famous hermit crab-anemone symbiosis.
A brief chapter is devoted to mechanisms regulating symbiotic relationships, with emphasis on the light which may be shed on problems of parasitism and disease.