THE AMERICAN BOTANIST 143 



crop of this State, worth at 1919 prices about $35,000,000. 

 When the July rainfall is three and a quarter inches, the yield 

 is 15,000,000 bushels greater than when it falls short of this 

 amount by half an inch. Each quarter of an inch increase 

 between the totals of two and four inches means an added 

 value of about $7,800,000. Taking the four great corn-grow- 

 ing States of Indiana, Illinois, Iowa and Missouri, the addition 

 of half an inch to a total of two and three quarters inches adds 

 ten bushels per acre to the crop yield on an average. This thin 

 layer of water is worth at present prices about $13 an acre, 

 or a total for these four States of the Corn Belt of the signifi- 

 cant sum of $4,000,000,000. Truly if corn is king in this 

 region, water is the power behind the throne. — From an article 

 by Thomas A. Blair in Scientific Monthly. 



Thk Axciext Bacteria. — Bacteria are at once the 

 simplest and the oldest of living things on our planet. Not so 

 long ago, it was taught that the bacteria are degenrated re- 

 lations of the green or blue-green algae, but the investigators 

 of the earth's crust find evidences of bacteria in the earliest 

 strata that contain organic remains and now regard them as 

 the original "old settlers." Finds of this nature seem to have 

 [)ushed back the date of the origin of plants and animals for 

 millions of vears. The earliest bacteria appear to have ob- 

 tained their energy by oxidizing substances other than those 

 containing carbon. The sulphur and iron bacteria, which are 

 undoubtedly responsible for some of our iron deposits are 

 among the number. Some such forms have probably given 

 rise to the higher species of plants that get their energy through 

 photosynthesis. If we may judge from the evidence of the 

 rocks, the early bacteria were not disease producing. Bacterial 

 diseases have originated as evolution has progressed. The first 

 animals and plants evidently were not confined to any definite 

 length of life, but lived on in placid enjoyment of their en- 



