THE ORIGIN OF LIFE 167 



possessed, and that the life-histories of these 

 multitudinous forms of microscopic life were 

 not then elementary biology as they are to-day. 

 To explain the appearance of these living 

 organisms, an English cleric, Needham, and 

 the great naturalist, Buff on, evolved the theory 

 that a force, called productive or vegetative 

 force, existed, which was responsible for the 

 production of organized beings. Buff on elabo- 

 rated the theory that there were certain 

 unchangeable parts common to all living 

 things. These ultimate organic constituents 

 he supposed capable of taking various moulds 

 or shapes which constituted the various 

 living creatures. After death, these ultimate 

 constituent parts were supposed to be set 

 free and become very active. Uniting with 

 one another and with other particles they 

 formed swarms of microscopic creatures such 

 as the microscope revealed, or even produced 

 earthworms and larger fungi. 



Needham took putrescible organic matter 

 and enclosed it in vessels which he placed 

 upon hot ashes to destroy any existing 

 animalculse ; yet, later, in these fluids, he 

 found animalculse which were not observed 

 there in the beginning. 



It was in refutation of this work that the 

 Abbe Spallanzani carried out the remarkable 



