SOCIETY OF CENTEAL ILLINOIS. 167 



under the microscope often shows a maze of living beings most 

 wonderful. The waters of running streams have them to some 

 extent, and peculiar kinds make the ocean their home. The air, like 

 water, is pure or impure, and is often filled with living, moving, 

 multiplying things. They are found in floating dust of organic 

 origin, in the atmosphere of close rooms, in thickly-crowded streets, 

 and particularly over decomposing filth. They are unavoidab y 

 inhaled with every breath. In the open country few of them are 

 found, and the same may be said of desert regions. 



The cyclone is, no doubt, a purifier. The air, during damp, 

 close weather in summer and autumn, is freighted with myriads. 

 These micro-organisms are found in the slime on vessels wherein is 

 standing-water : on the surfaces of many articles of cold food when 

 set away for some time, for instance, boiled potatoes and cooked 

 meats ; some forms of yeast ; sour milk always has them in swarms, 

 and so do liquids from fruit, when forming into vinegar. They are 

 always present in pus, or matter from suppurating wounds, in dis- 

 charges from boils and tumors on the animal organism, in the matter 

 gatheriug on the teeth, which is full of them, and some kinds retain 

 tlieir activity in the stomach. In health the blood is free from them, 

 but in some diseases myriads of them are swept along the currents 

 of the blood vessels. It is easy to see how the blood gets out of 

 order. A few words regarding the color, shape and size of these 

 organisms may be interesting. As a rule, they are white, and when 

 numerous in water it looks milky ; but of different species each has 

 its peculiar color, — as red, blue, yellow or green. In shape they are 

 round, oval, cylindrical, or like a thread. In size, from one twenty- 

 five thousandth to one fifty thousandth of an inch in diameter. It 

 requires a magnifying power of ten thousand areas to see one of 

 ordinary size — 100 diameters, — and ten times as great power is 

 required to make out its shape. 



If a man was magnified 1,000 times — which is the lowest power 

 by which one of the largest bacteria may be seen, — he would be one 

 mile high. From one hundred to two hundred and fifty of these 

 bacteria are required, when placed side by side, to be as wide as the 

 thickness of common writing paper. They are the smallest living 

 organisms known to man. They multiply very rapidly, even double 

 every hour under favorable conditions. Don't let us conclude that 

 bacteria are "always injurious, and only injurious in their effects." 

 This is far from the truth, "They are, primarily, the agents of 

 decay" ; still, in this sense, untold good results from their activities. 

 *■ It is, indeed, no more startling than true to say the organic world 

 is indebted to them for its existence," Were it not for the destroy- 

 ing, decomposing work of the bacteria, which changes animal and 

 vegetable organic bodies into new forms — liquid and gaseous, — so 

 as to form material for new structures. Then organic matter, animal 



