Developmental History of Infusorial, Animal Life. 359 



organic germs ; on the hypothesis that animalcules, like other 

 animals and plants, are produced from germs or eggs, which 

 might be in the water and yet so excessively minute as to be 

 easily overlooked, and only awaiting the proper conditions 

 for their speedy development j or, on the other hand, supposing 

 them to be floating about in the air, they would fall into or 

 enter any vessel containing organic matter in a state of decom- 

 position and there develop. Schultze's experiment, then, 

 looked very like a conclusive one, for no sooner were measures 

 taken to destroy the germs, supposed to be suspended in the 

 air, than the infusion was kept free from animalcules ; and no 

 sooner was the air allowed to enter in the ordinary manner 

 than both animal and vegetable life abounded. It was thought, 

 however, by M. Morren, that air in its passage through sul- 

 phuric acid underwent some alteration which affected its power 

 of supporting life ; and upon putting this to the test, he found 

 that air passed through sulphuric acid was incapable of sus- 

 taining life. We have then, M. Pouchefr's experiments, which 

 are of a most imposing character. He announced that there 

 was nothing in either Schnitzels test or Morren's correction, 

 for he declared that in following the former's experiment in 

 every particular, and also in repeating it with fresh precau- 

 tions, he could constantly find both plants and animals in an 

 infusion in which every organic germ had been previously 

 destroyed, and to which the air only had access after passing 

 through concentrated sulphuric acid, or through a series of 

 porcelain chambers kept at a red heat. M. Pouchet even goes 

 farther than this. He determined to substitute for atmospheric 

 air, artificial air ; this he introduced into a fiask containing an 

 infusion of hay, the hay having previously been subjected for 

 twenty minutes to a heat of 212° P. He thus guarded against 

 the presence of any germs in the infusion or in the air. The 

 whole was then hermetically sealed ; but in spite of all these 

 precautions, both plants and animals appeared in the infusion. 

 He repeated the experiment with pure oxygen gas instead of 

 common air and with similar results. 



Professor Yfyman instituted a series of thirty-three experi- 

 ments, prepared in different ways, in which solutions of organic 

 matter, some of them previously filtered, having been boiled 

 at the ordinary pressure of the atmosphere for a length of time 

 varying from fifteen minutes to two hours, were exposed to air 

 purified by heat. In only four were the contents of the flasks 

 unchanged when opened; in all the rest Bacteriums, Vibrios, 

 Ferment-cells, Monads, or Kolpoda-lihe bodies were seen, some 

 of them having ciliary movements. In nearly every instance 

 their presence was indicated by the formation of a film, which 

 appeared in some, on the second, and in others not until the 



