Problems of Thermophilic Life in Polar Regions 155 



glucose agar shake tubes were also prepared from the bird and 

 seal specimens. 



This complete failure to find thermophilic bacteria in speci- 

 mens from Antarctica is puzzling since they have surely been 

 introduced many times during the last 50 to 60 years. It is 

 true that there are no large accumulations of decomposing organic 

 material in this part of Antarctica, but man along with dogs 

 and horses have been in this area repeatedly for half a century. 

 The absence of thermophilic bacteria from the horse manure 

 is especially interesting since this type material has repeatedly 

 been used as a source of thermophilic cellulose fermenting bac- 

 teria. It may be that only anaerol^ic thermophilic bacteria were 

 present and that these were undetected because only aerobic 

 conditions were used on this culture. One would hardly expect 

 that all aerobic spore-forming thermophilic bacteria would have 

 died during the 45 years of exposure of Antarctic conditions 

 since more than 1,000 coliform bacteria per gm were still present 

 in tlie sample examined. 



The relative abundance of aerobic thermophilic bacteria in 

 arctic regions and their absence or relative scarcity in antarctic 

 regions where they have been sought has led me to the following 

 speculations. 



1. Arctic regions are in general not as inhospitable as is 

 Antarctica. There is an abundant growth of grasses, lichens, 

 mosses and flowering plants in arctic areas free of ice and snow 

 during the summer. Antarctica, on the other hand, is devoid of 

 grasses and flowering plants except on parts of the Palmer 

 Peninsula which extends northward to approximately 63° S lati- 

 tude. Even the antarctic mosses and lichens generally barelv 

 hold their own against cold, dryness and a scouring wind. There 

 is no accumulation of plant remains to help with the formation 

 of a true soil which could support a large microbial population. 



2. Arctic animals are quite numerous and range in size 

 from the lemming to the musk ox and caribou. Both herbivores 

 and carnivores are included. They supply variety to the organic 

 material and also continually reinoculate the soil with mesophilic, 

 (and possibly thermophilic bacteria) from their digestive tracts. 

 The effect of the lemmings and the other animals on the arctic 



