96 The Science of Life. 



careful work of Von Siebold, Leuckart, Kuchenmeister, 

 Van Beneden, and others. The working out of the 

 life-history of the common tape-worms or of the liver- 

 fluke are familiar cases in point. 



Aristotle had excepted the higher animals from the 

 possibility of spontaneous generation, Redi had de- 

 siow Death stroyed the supposed case for insects in 

 of the Theory carcasses, even the spontaneous origin of 



of Spontane- , ., , . ,,r i 



ousGener- endoparasites was becoming doubtful; in 

 ation. short, the flimsy evidence began to crumble 



away. This was partly due to the development of 

 criticism, partly to the work of the early microscopists 

 and anatomists, who showed how complex most of the 

 lower animals are; and partly perhaps to a growing 

 sense of the physiological gulf between the living and 

 the not-living. 



But Redi's experiments were held to controvert the 

 Scriptures, and we find the Scotch priest Turbervill 

 Needham trying hard (1750) to give experimental proof 

 of the spontaneous origin of wheat-eels (small Nema- 

 tode worms), an attempt which Voltaire derided with 

 bitter sarcasm. But no experimenter is to be despised, 

 and Needham did good service in directing attention 

 to a weak point in the case against spontaneous gener- 

 ation. He showed that animalcules (Infusorians and 

 the like) appeared even in decoctions which had been 

 boiled and corked up. As we should now say, this 

 result was due to imperfect sterilization and imperfect 

 corking of the tubes; but it was used by Buffon, who 

 was much interested in Needham's work, to bolster up 

 a pet theory of his, that life resided in indestructible 

 organic molecules, and that these were liberated after 

 death or in decomposition as the aforesaid Infusorians 

 or animalcules. 



On the other hand, the Abb6 Spallanzani (1729-99), 

 who made many interesting though often careless and 

 ruthless experiments, criticised Needham's researches, 

 and anticipated the modern practice of sterilization by 

 showing that even minute forms of life did not develop 

 in decoctions which had been well boiled and then her- 

 metically closed up. 



