MICRO-ORGANISMS. 771 



moving from place to place, although many enjoy this freedom for 

 only a part of their lifetime, and then hecome adherent or attached to 

 foreign bodies for the rest of their existence. But even with the 

 most rapid, free swimming forms, so little distance can be accom- 

 plished in their almost momentary lives, that their voluntary progres- 

 sions can have little or no effect on their geographical distribution. 

 In this they are creatures of chance or circumstance. Multiplying in 

 myriads, and being too small and weak to resist the elements, they are 

 constantly swept about in currents of water or air, and in the moisture 

 on the surfaces of moving animals, etc. Well-authenticated observa- 

 tions show that with the evaporation of ponds and other waters con- 

 taining swarms of these little animals, many encyst themselves within 

 delicate capsules formed of an exudation, which hardens the body-sur- 

 face ; they then dry up and become as particles of dust, which are 

 wafted from place to place by the winds, and for weeks or months 

 may lie in the mud, dust, or snow, on hay, moss, branches of trees, 

 etc. Others decompose, but leave behind their germs, which are dis- 

 tributed in the same way. By these means they are scattered every- 

 where, and those which chance to fall into favorable situations survive 

 and produce swarms of progeny, while others, falling on bad ground, 

 perish. Thus they are ready to do their appointed work, whenever 

 and wherever it is needed. It is commonly thought that pure drink- 

 ing-water is filled with these microscopic creatures, and it is sometimes 

 said that they constitute the life of the water, while in their absence 

 it becomes dead, stagnant, and often slimy, green, and unfit for use. 

 All this is the opposite of the facts. Pure water is not inhabited by 

 organisms ; on the contrary, stagnant water or impure water alone 

 affords them subsistence. They hasten the destruction of dead ani- 

 mal and vegetable matters the water may contain, causing for the time 

 being an infusion or fermentation, which results finally in the purifi- 

 cation of the liquid in question. 



The bodily corruption in diseases, whether contagious or not, is not 

 caused alone by the swarms of infesting organisms associated there- 

 with, but is simply their cause, a sustenance for them, itself making 

 their existence and multiplication possible. 



The unaccounted-for readiness of these animalcules to spring up 

 wherever decaying organic matter existed, first suggested the name 

 infusoria, and led to the early false opinions that they were generated 

 by the decomposition and fermentation of organic bodies, and to the 

 modern reformed theory of spontaneous generation. 



Strangely seeming, yet true, stagnation, death, decay, are replete 

 with life when viewed through lenses, so that it has become a scientific 

 doctrine that all organic decomposition and fermentation is assisted 

 and sustained by these tiny creatures. Hence we may regard them 

 as the most important scavengers of earth, water, and air. 



While their devouring work is as a "bottling up" of injurious and 



