THE GENESIS OF LIFE. 161 



composing meat. Placing this infusion of putrefying matter 

 in a flask, Needham applied heat thereto, and after boiling 

 the liquid, and carefully corking and sealing it, contended 

 that he had adopted a mode of procedure well adapted to 

 furnish evidence for or against spontaneous generation. As 

 Redi had excluded the flesh-flies by the gauze he placed 

 over the meat, so Needham aimed at protecting his fluid by 

 carefully corking his flask ; whilst he also assumed that the 

 heat applied to its contents would effectually destroy any 

 living beings it might originally have contained. Ensured, 

 thus, in his ideas, from outward contamination, and guarded 

 equally from any inherent or internal source of life-develop- 

 ment, the fluids experimented upon were left to subside. 

 The appearance of animalcules in his protected fluids would 

 form, to Needham's mind, a clear proof that they must have 

 been generated de novo, or from dead matters contributed 

 by the fluid; for had he not destroyed all living things 

 within, and excluded all life proceeding from without ? The 

 opposite result of barrenness in the fluid would, of course, 

 weigh powerfully in the opposite direction, and determine a 

 belief in Redi's idea, that, having destroyed and excluded 

 all sources of life-development, no living things could appear 

 in the flasks. The result of Needham's experimentation was 

 affirmative in character. Sooner or later, the boiled liquids 

 became turbid and muddy from the development of organ- 

 isms, and microscopic examination showed an abundance of 

 animalcular life in the flasks. That Needham should, 

 therefore, have become a staunch advocate of spontaneous 

 generation cannot be accounted other than a natural result 

 of his interrogation of nature. Repeated experimentation 

 seemed to place his belief on a still surer basis, and it thus 

 appeared that Redi's doctrines were in some danger of being 

 overthrown by the march of inquiry, and by investigation 

 directed in new lines of research. 



It is both curious and instructive to note that Needham's 

 experiments appeared to afford support to a singular theory 

 of the nature and origin of living bodies, which was enun- 



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