Critical maximum temps. El Kabstum 1954 Bufo canorus and Bufo boreas Oct. 5 Exp't. # 1 (cent.) wate r VA B 10:48 A.M. 40.1 [38.8] 39.7 - canorus weak climbing movements 10:46. Crouched position one minute later. In distress 10:49 40.8 39.2 40.2 - head wogging, boreas for :51 41.2 39.7 40.9 not moved from crouched positin. -no canorus movement since :53 40.0 10:49 A.M. cloacal temp of B. boreas 10:53 is 39.8° C. it is in severe shock. No righting reflex, legs extended backward, and shrunken appearance sides of body. B. canorus extended legs out 10:53 and head lowered. Cloacal temp. at 10:55 of this animal in deep shock 39.6° C. neither tood slowed gular movements or could right itself when placed on its back. Placed both on dorye, cool towel 10:56. B. boreas was breathing and showed a righting reflex by 10:59. B. canorus showed reflex of eye-lid when probed by this time. By 11:30 A.M. both were moving about. Both toods were apparently subjected to temperatures higher than their true critical minimum, so the cloacal temps. are not a true indication of lowest temp. at which heat shock is evident i.e. critical maximum. Results Exp't. 1 critical max. Bufo boreas = 37-38° C. Bufo canorus = 38-39° C.