SPONTANEOUS GENERATION. 49 



In many instances undoubted organisms in a living 

 state were identified, but the number present varied 

 greatly in different flasks. The cause of the difference 

 was not in all instances clear. In many cases the 

 germs were so very minute, that I am quite sure they 

 would have completely escaped observation if an 

 object glass magnifying upwards of 1,000 diameters 

 linear had not been employed. These observations 

 necessarily lead us to conclude that the failure of 

 observers who have worked with quarters and object 

 glasses magnifying less than 500 diameters, is easily 

 accounted for. Even Hallier, I believe, carried on his 

 more recent observations with very low powers, and I 

 believe the observations of both Pouchet and Pasteur 

 are open to objections upon the same grounds. 



Some of the organisms discovered in Dr. Child's 

 infusions are represented in Figs. 17 to 20, plate III, 

 from drawings made by myself. The large dumb- 

 bell shaped bodies represented in Figs. 17, 18, are 

 not organisms, but crystals. They could be readily 

 distinguished from the living forms by their high 

 refractive power, larger size, and absence of any 

 movement. 



It was supposed that boiling was fatal to all living 

 things ; then it was proved by experiment that 

 some living things, under certain circumstances, did 

 live in spite of being subjected to a temperature even 

 above that of boiling water. But was it therefore 

 necessary to assert authoritatively that no living 



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