Interest in the study of the physiology of reproduction is of relatively recent date and has developed largely in the last forty years. Interest in the physiology of reproduction of the invertebrates is of even more recent date. In fact, the most complete and up-to-date compendium of compara tive animal physiology (1) omits the subject entirely. Yet it is known that in the invertebrate world exists a diversity of modes of reproduction from primitive to highly evolved, asexual3 as well as sexual (2,3,125,126). Here is to be seen, so to speak, the evolution of the animal reproductive process, a procession of nature's fascinating experiments. Investigators have to some extent realized the opportunities for such studies, and many articles on the physiology of reproduction in invertebrates are widely scattered in the literature in a variety of journals. Neglect of discussion of the physiology of the reproductive processes of the invertebrates, then, has not been for lack of material but rather for lack of a synthesis of the existing literature.It would be impossible in a single brief review to cover completely the physiology of invertebrate reproduction, desirable as it might be. Rather, this review considers only the annual reproductive cycles of marine inver tebrates, with special emphasis on papers which include interesting view points, experimental approaches, or provocative material.A few general references which give considerable information on annual reproductive cycles of marine invertebrates are: the Handbook of Biological Data (4), in which is found a table containing breeding seasons and related data for invertebrates from various places; a book on methods for obtaining and handling marine eggs and embryos (5) of East Coast invertebrates (particularly for animals from the Woods Hole area); a paper (6) on New Zealand invertebrates; two books (7, 8) and several papers (9, 10) on West 1 The information in this article covers the literature as far back as seemed feasible to go and includes citations up to August, 1958. Wherever possible, reference is given to key review articles which give references to older literature. If important or inter esting work was omitted, it was unintentional.2 I am indebted to the staff of the Stanford Biological Libraries: Mr. F. Falconer, Chief Science Librarian, Miss Joanne Dandois, and Mr. Michael Sadoski without whose help it would have been impossible to make the extensive bibliographic search.3 Asexual reproduction occurs in many groups of animals, among them the Pro tozoa, Porifera, Coelenterata, Platyhelminthes, Rotifera, Tunicata, and certain Annelida (Polychaeta). These are dealt with in general works (2, 3) on the inverte brates. Considerable research on polychaetes is referred to by Durchon (123). Dode caceria, one of the most interesting of the polychaetes, has a remarkable capacity for asexual reproduction, and Martin's paper (125) and references cited by him should be consulted for information. 547 Annu. Rev. Physiol. 1959.21:547-576. Downloaded from www.annualrevie...
