BERRY 



further cooled. These facts have relevance only to serve as warn- 

 ings against any attempt to generalize about the hypothermic in- 

 fluence on host- parasite interaction. The specific body temperature 

 and its duration must be specified in reporting results, and con- 

 clusions can never be presumed generally applicable unless data are 

 available to prove it. 



The two sessions tomorrow will attempt to answer the question: 

 Does cold predispose experimental animals (and man) to infectious 

 disease, and if so, what diseases and under what conditions? We are 

 unusually fortunate in having two of the world's authorities on in- 

 fectious diseases to serve as moderators, I refer, of course, to 

 Dr. Walter Nungester and to Sir Christopher Andrewes. Dr. Nun- 

 gester has specialized primarily as a bacteriologist and Sir Chris- 

 topher as a virologist. Their names must certainly be included in 

 the special list of experts whose willingness to participate con- 

 tributed so much in attracting to the Symposium such an illustrious 

 group of participants. We are delighted to welcome and express our 

 deepest gratitude to Drs, Miya,Previte,andMiragliafor the reports 

 they are to give on work with bacterial diseases. We are equally 

 fortunate in having such distinguished virologists interested in this 

 area of research. I refer, of course, to the Drs. Walker, Metcalf and 

 Sulkin, and to perhaps the most versatile of us all, Dr. Marcus, who 

 is at home with both bacterial and viral diseases as well as with 

 immunology. 



A warning has been sounded against the pitfalls of generalizing 

 from experiments with hypothermic animals unless sufficient know- 

 ledge justifies it. A similar warning must be issued in regard to 

 cold exposure and change in susceptibility to infection. Differences 

 in interpretation of results, differences in experimental design, and 

 differences in findings are to be not only anticipated but desired. It 

 is in this way that breadth of understanding is best acquired. But 

 let us reflect a moment on some of the obvious difficulties in this 

 type of work. At whattemperature are the animals exposed? "Cold", 

 according to the literature, can be anything from 15° C to 20° C 

 down to refrigerator temperatures, about 5° C, or deap freeze, 

 -10° C to -20° C, or it can be an arctic blizzard of -45° C. How 

 long are the animals exposed? This can range all the way from 

 continuous exposure, beginning with challenge, to an infinite varia- 



