As a source of information on neuroanatomical research methods this Volume is not without precedent. In 1957, at the initiative of Dr. W. F. Windle, a conference was held at the National Institutes of Health, the proceedings of which, edited by Dr. Windle and published by C. C. Thomas under the title "New Research Tech niques of Neuroanatomy," rapidly became something like a standard reference in the field of Neuromorphology. The present editors were emboldened to seek support for a second expose of contemporary research methods in Neuroanatomy by the success of this earlier publication, as well as by the consideration that the years elapsed since its appearance have been, perhaps, more productive of new research methods and strategies in Neuroanatomy than were any dozen consecutive years since the golden decades of the 1870's and 1880's. The decision, which methods to include in this conference, has been a difficult one. For reasons of space alone it would have been impossible to do equal justice to techniques approaching the brain as a neuronal system, the brain as a tissue, or the neuron as a cell. As a brief inspection of the contents of this volume will show, the weight of choice fell upon the first of these alternatives. The reader will find, further more, that not all of the book is devoted to new methods in the strict sense."

Ever since the behavioral work of Lissrnann (1958), who showed that the weak electric discharges of some families of fish (hitherto considered useless for prey capture or for scaring away enemies) are part of a strange sensory system, these fish have attracted attention from biologists. The subsequent discovery of the electroreceptors in the skin of gymnotids and mormyrids (Bullock et al. 1961; Fessard and Szabo 1961) and the evidence that the ampullae of Lorenzini of nonelectric sharks and rays are also electro- receptors (Digkgraaf and Kalmijn 1962) was a start for a lively branch of physiological, anatomical, and behavioral research. Many fmdings of general importance for these fields have made the case to which extremes the performance of the central and peri- pheral nervous systems can be driven. Among those fmdings is the temporal accuracy of the pacemaker of some high-frequency fish which controls the electric organ, pro- bably the most accurate biological clock (coefficient of variation < 0. 0 1 %, Bullock 1982). The functional analysis of the pacemaker cells and their axons has established most of our knowledge on electrotonic synapses, the alternative to chemical synapses (Bennett et al. 1967), and of the implications of axonal delay lines for achieving extreme synchrony of parallel inputs to postsynaptic elements (Bennett 1972; Bruns 1971).