"THE MIMIC FIRES OF OCEAN" 1323 



tion is probably due to excessively fine hairs at their 

 extremities, which, moving to and fro in the water, 

 act the part of oars. These cilia have not been found 

 in all forms of bacteria which move, but their pres- 

 ence is inferred, since every advance in the study of 

 motile forms increases the number of bacteria which 

 are seen to possess them. 



These light-producing bacteria are known as 

 photo-bacteria, and so far some half-dozen varieties 

 have been distinguished and named. The names in 

 such cases are usually either given from the locality 

 of their appearance (thus, photo-bacterium Bal- 

 ticum, found in the Baltic), from their discoverer 

 (for example, photo-bacterium Fischeri, after Pro- 

 fessor Fischer), or from some striking attribute (to 

 wit, photo-bacterium phosphorescens, the commonest 

 light-giving species). 



A Dutchman named Beyerinck has made a special 

 study of these photo-bacteria, and has experimented 

 with them in a great number of ways to determine, 

 if possible, why they should thus become illuminated, 

 and if the light plays any notable part in their life- 

 history; but his results are, seemingly, all more or less 

 of a negative nature. He can not find that it has 

 any very important function. The breathing of these 

 tiny organisms is not, apparently, in any way bound 

 up with it; their nutrition, growth, and development 

 go on quite well even if they are placed under such 

 conditions that their luminosity is arrested; in no 

 way, indeed, is it a vital process. It only seems to 

 depend on the food which the bacteria feed upon and 

 the presence of oxygen. Given suitable food and 



