Book excerpt: This second edition offers a comprehensive overview of the physiological functions of vertebrate kidneys from a comparative viewpoint, with particular emphasis on nonmammalian vertebrates. The topics covered include renal structure; glomerular ultrafiltration; tubular transport of inorganic ions, organic substances, and fluid; and urine dilution and concentration. Mammalian renal function is only considered for purposes of comparison with nonmammalian renal function and as a frame of reference for some of the discussions. The major findings on nonmammalian renal function and the important unanswered questions raised by those findings are described in detail. As such, the book provides comprehensive information on comparative renal function for biological scientists and advanced students of biology with some knowledge of physiology and a desire to know more about renal function in vertebrates, and for mammalian renal physiologists who wish to obtain a broader view of renal function.