“…Gradually the problem emerged to find the proper minimal conditions which would inactivate and, thereby, characterize all reagins derived from atopic persons. It became evident that the conditions 56 C for 4 hr or less would produce 100% inactivation of reagins in most atopic sera (9,131,176,243,255,348,353,390). A somewhat less commonly used set of conditions quite comparable in results is 60 C for 1 hr or less (42,255,257).…”