2 U. S. NATIONAL MUSEUM BULLETIN 217 



exist in proximity to man, whereas natural selection proceeds accord- 

 ing to natural law. 



Thus, in spite of the progress in biology resulting from the applica- 

 tion of new physiological instrumentation in the laboratory, we 

 usually have had to speculate about the mode of life of animals that 

 survive under those particular natural conditions which the physio- 

 logical processes we were able to study in the laboratory seemed quite 

 inadequate to cope with. 



For example, the prolonged dives of whales and seals are impossible 

 for land animals, which are characteristically intolerant of inter- 

 ference with breathing. But as soon as I began to observe and measure 

 characteristics of respiration in diving animals, I found that only a 

 small range of the respiratory capability of mannnals had come to 

 view because the laboratory study had been limited to a few domesti- 

 cated species whose rapid breathing concealed the basically discon- 

 tinuous process of respiration which supplies oxygen for continuous 

 metabolism. I found, for example, that when a seal dived the pro- 

 longed intervals between its breathing magnified the appearance of 

 the respiratory reserves and lengthened the cycle of breathing so that 

 its sequential processes could be separated. 



As a further consequence of their adaptation of respiration to long 

 periods of interrupted breathing a few species of mammals and 

 birds can enter waters which are well stocked with cold-blooded 

 animals. These warm-blooded birds and mammals, with their 

 air-breathing habit primarily suited to land, have a physiological 

 mechanism superior in its output of power to the cold-blooded mech- 

 anisms. This special adaptation of respiration has enabled them to 

 use the superiority of their warm-blooded metabolism for the exploita- 

 tion of an aquatic environment. 



Plans for Arctic Studies 



A concern for these subjects led me, during World War 11, to a tour 

 of duty in the Air Force, during which I was engaged in developing 

 techniques for human survival in the Arctic, and my interest in that 

 region thus become aroused. "Wlien, therefore, in 1946 I returned to 

 the Edward Martin Biological Laboratory at Swarthmore, I began, 

 with some colleagues who, like myself, had just been released from 

 the confinement of military service, to examine the prospects for 

 further investigations in the Arctic. We saw that the establishment 

 of routine transarctic air transport was opening the region to common 

 experience, and that a new phase of Arctic exploration, involving 

 comprehensive and intensive scientific research, was required to pro- 

 vide the information upon which would depend the establishment of 

 extensive human life there. 



