THE CRITICAL THERMAL MAXIMUM - HISTORY AND CRITIQUE

We reviewed 725 papers published since Cowles and Bogert's paper on th ermal tolerance (R.B. Cowles and C.M. Bogert. 1944. Bull. Am. Mus. Nat . Hist. 83: 261-296) to create a data base of studies that used critic al thermal maximum or lethal-temperature methods. We found data from 3 88 of these papers to provide a historical and taxonomic review of var ious methodologies used in measuring tolerance of high temperature. We conducted this literature review of previous studies to (i) describe the history of the study of thermal tolerance and show the chronologic al trends in the use of lethal temperature and critical thermal maximu m methods, (ii) illustrate the diversity of taxa used in thermal-toler ance studies, (iii) summarize the diversity of protocols (i.e., end po ints, heating rates, acclimations, etc.) used for determining thermal tolerance, (iv) provide physiological reasons why the onset of spasms is more meaningful biologically than the loss of righting response, an d (v) discuss the difficulties in using data from studies in which wid ely divergent methods were used and the importance of obtaining compar ative thermal-tolerance data for comparative physiology. The adoption of the onset of spasms as a standard end point would allow for valid c omparisons of data from different studies and among taxa, an important consideration for current investigations of comparative physiology th at use the comparative phylogenetic method.