R. B. Freeman

The present volume covers the physiology of the visual system beyond the optic nerve. It is a continuation of the two preceding parts on the photochemistry and the physiology of the eye, and forms a bridge from them to the fourth part on visual psychophysics. These fields have all developed as independent speciali­ ties and need integrating with each other. The processing of visual information in the brain cannot be understood without some knowledge of the preceding mechanisms in the photoreceptor organs. There are two fundamental reasons, ontogenetic and functional, why this is so: 1) the retina of the vertebrate eye has developed from a specialized part of the brain; 2) in processing their data the eyes follow physiological principles similar to the visual brain centres. Peripheral and central functions should also be discussed in context with their final synthesis in subjective experience, i. e. visual perception. Microphysiology and ultramicroscopy have brought new insights into the neuronal basis of vision. These investigations began in the periphery: HARTLINE'S pioneering experiments on single visual elements of Limulus in 1932 started a successful period of neuronal recordings which ascended from the retina to the highest centres in the visual brain. In the last two decades modern electron­ microscopic techniques and photochemical investigations of single photoreceptors further contributed to vision research.

Are they needed? To be sure. The Darwinian industry, industrious though it is, has failed to provide texts of more than a handful of Darwin's books. If you want to know what Darwin said about barnacles (still an essential reference to cirripedists, apart from any historical importance) you are forced to search shelves, or wait while someone does it for you; some have been in print for a century; various reprints have appeared and since vanished." —Eric Korn, Times Literary Supplement Charles Robert Darwin (1809–1882) has been widely recognized since his own time as one of the most influential writers in the history of Western thought. His books were widely read by specialists and the general public, and his influence had been extended by almost continuous public debate over the past 150 years. New York University Press's new paperback edition makes it possible to review Darwin's public literary output as a whole, plus his scientific journal articles, his private notebooks, and his correspondence. This is complete edition contains all of Darwin's published books, featuring definitive texts recording original pagination with Darwin's indexes retained. The set also features a general introduction and index, and introductions to each volume.