1322 THE STORY OF THE UNIVERSE 



surface of their bodies; others have declared that 

 it is due to a subtle power of the fish itself a form 

 in which the energy of life shows itself under certain 

 conditions, just as this energy may be exhibited in 

 heat, or motion, or electricity; others, again, have 

 ascribed it to direct absorption and transmission of 

 the light of the sun, and so on. Many theories have 

 been elaborated, but none convincingly. 



But now, it is asserted, the secret is laid bare. 



It is wonderful how many secrets the searching 

 light of the Nineteenth Century is claiming to reveal. 



It is only lately that any very serious effort has 

 been made to study this phenomenon, but the research 

 has been abundantly rewarded, for it is now pretty 

 certain that the luminosity is due to the presence in 

 the water of various kinds of bacteria. 



Now, bacteria are the very smallest living organ- 

 isms of which we have cognizance. Millions of 

 them can lie on a penny; therefore, to produce the 

 gleaming appearance recognized by us as phos- 

 phorescence, they must be present in numbers too 

 enormous even to contemplate with our finite minds. 

 It would be immeasurably easier to reckon with the 

 stars for multitude than with these phosphorescent 

 bacteria. They are colorless, rodlike bodies, only 

 known to us in the land revealed by the highest 

 powers of the microscope, and careful comparison 

 shows minor differences among them. For instance, 

 some of them are capable of independent motion 

 we can hardly call it swimming others are non- 

 motile, some are inclosed in a jelly-like covering, 

 others are without this sheath. Their power of mo- 



