WHAT ARE LIVING UNITS? 87 



bacteria in the interior of adobe bricks from old Spanish Missions 

 and from Aztec and Inca ruins, as well as in coal samples taken 

 1,800 feet below the surface of the earth. He believed that the 

 peat-like coal-forming material of past geologic ages was extremely 

 rich in bacteria, and that some of their spores still survive. He 

 also isolated an autotrophic bacterium from petroleum coming 

 from a well 8,700 feet deep. 4 Confirmation of this work will be 

 welcomed. 



To test the viability of seeds, Dr. W. J. Beale of Michigan Agri- 

 cultural College in 1879 buried 20 different kinds of plant seeds, 

 and had samples taken every five years for test. After forty years' 

 burial, half of the species produced sprouts. 5 In 1902 Dr. J. W. 

 T. Duvel of the U. S. Department of Agriculture buried seeds of 

 107 species, and found that 69 species grew after 10 years' burial, 

 and 20 species after 20 years' burial. Most hardy were the seeds 

 of wild plants and weeds. Cereal, legume, and cultivated plants 

 generally failed to grow; apparently they depend upon human 

 help to perpetuate themselves. 6 



Becquerel 7 tested 550 species of seeds which had been stored 

 at the Jardin des Plantes in Paris for from 25 to 135 years. 

 Nothing older than 80 years germinated. I have been assured by 

 the late Dr. A. Lucas, chemist of the Cairo Museum, that the so- 

 called viable "mummy wheat," sometimes "found" by native 

 guides in Egyptian tombs, represents recent crop material placed 

 there presumably by the finders. The fraud has been often ex- 

 posed. R. Whymper and A. Bradley report 8 that a sample of 

 English wheat stored under conditions of desiccation favorable to 

 longevity, showed 69 per cent germination after 32 years' storage. 

 Though exhaustion of the sample (1945) ended this series of tests, 

 the yearly record indicates that an estimated extreme limit of life 

 of 50 years is rather an understatement. 



On visiting Palestine a few weeks after unusually heavy rains, I 

 saw a gorgeous, multicolored floral display on the normally bare 

 hills. And in 1930, after one of the rare rainfalls in the desert of 

 Death Valley, California, there was a luxuriant growth of plants, 

 arising from long-dormant seeds, many probably carried there by 

 the winds. 



In 1943 a slightly spotted greenish cast was noticed on the gray- 

 ish limestone wall of the corridor opposite the elevator shaft in 

 the Carlsbad Caverns, New Mexico, about 750 feet below the 

 surface; it gradually spread and became grass-green. In 1941 there 



