178 liebig's statement. 



admirable cause which removes from water all 

 substances injurious to the life of the higher 

 classes of animals ; and creates in their place 

 nutritive matters for the sustenance of plants, 

 and the oxygen indispensable to the respiration 

 of animals." Again, he observes, "The mfu- 

 sorial animalculae cannot be the causes of 

 putrefaction — of the production of poisonous 

 matter deleterious to plants and animals — but 

 an infinitely wise intention designs them to 

 accelerate the transition of the elements of 

 putrefying substances into their ultimate pro- 

 ducts." The reason of their presence in these 

 places as regards themselves obviously is, that 

 in them they find the conditions suitable for 

 their development and sustenance. When these 

 circumstances take place, the universal presence 

 of the atmosphere through which their eggs 

 are diffused, causes them to make their ap- 

 pearance wherever the requisite state of things 

 for their vivification exists. They are, how- 

 ever, subject to the injurious influences of 

 actual putrefaction, and are killed by the sul- 

 phuretted hydrogen gas evolved during that 

 process. They abound in all decaying sub- 

 stances, but never in really putrid masses. 

 Their province, therefore, evidently is that 



