88 A CHEMICAL SIGN OF LIFE 



an appearance. The seeds really respire. Waller con- 

 sidered that our present chemical technique is not refined 

 enough to reveal to us the smallest and most infinitesimal 

 chemical changes which may be going on in the appar- 

 ently dry and perfectly dormant seed. He based his 

 hypothesis on two considerations: First, was the fact 

 that the seeds wear out, as shown by their losing their 

 power of germination and growth in proportion to the 

 length of time they have been kept. The deterioration 

 is more or less rapid, according to the nature of the 

 seed and the character of the protective coats, but in 

 every instance there is deterioration sooner or later. 

 He attributes this gradual deterioration to chemical 

 activity in the seed. 



In the second place, there was the fact, which he 

 showed by his electrical method, that a living seed not 

 only differs from the dead one in respect to its electrical 

 response, but that the amount of its response varies 

 according to its age. Thus, if he took a living seed, a 

 dead seed killed by heat, and a very old Egyptian seed 

 from about the Twelfth Dynasty (about 4,400 years 

 old) and determined their electrical response, he found 

 a very interesting result. The first, or living, seed gave 

 a large electromotive force, while the others, the old 

 as well as the dead, gave none. If he took a group of 

 seeds from crops of different years, he found that there 

 was also a gradual decline in the electrical response as 

 the seed became old. He considered this electrical sign 

 as the expression of the chemical changes which cannot 

 otherwise be determined, and such a sign of death, 

 according to him, is manifested long before microscopic 

 or chemical changes can be detected. 



