168 ORIGIN AND NATURE OF LIFE 



series of experiments mentioned above. He 

 suspected two defects in Needham's work, 

 just the same as those which Pasteur dis- 

 covered in the proofs of his opponents a 

 century later, namely, insufficient sterilization 

 by heat, and infection during the experiment 

 with living seed carried from outside, for 

 Needham had only closed his incubation 

 vessels with cork stoppers. 



At that early date Spallanzani actually 

 repeated the work in hermetically sealed 

 vessels, and used sterilization by boiling for 

 one hour. He writes, " I used hermetically 

 sealed vessels. I kept them for an hour in 

 boiling water, and after opening and examining 

 their contents after a reasonable interval, I 

 found not the slightest trace of animalculae, 

 though I had examined with the microscope 

 the infusions from nineteen different vessels." 

 Such work as this accomplished in the middle 

 of the eighteenth century deserves a prominent 

 place for its author in scientific history. 

 The same observer, it may be mentioned, also 

 discovered the antiseptic action of the gastric 

 juice. 



Needham's reply was that the prolonged 

 boiling had altered the character of the 

 infusion so that it was unable to engender 

 life. The witty pen of that master of satire, 



