INTRODUCTION 5 



which seemed to refute Eedi's. The results of these, 

 however, were not accurately supposed to prove 

 abiogenesis ; for BufFon assumed the existence of 

 " organic molecules " of some substance possessing 

 the inherent properties of life ; the moleculeis of this 

 substance being indestructible, and in modern nomen- 

 clature it might be regarded as an element endowed 

 with the potential properties of life. 



But Needham and BufFon were encountered by the 

 destructive facts brought forward again by an Italian, 

 the Abbd Spallanzani, who repeated Needham's experi- 

 ments. He showed that if the tubes used in these 

 experiments were subjected to the temperature of 

 boiling water for three-quarters of an hour and the 

 access of air eliminated by hermetically sealing the 

 tubes, no sign of living forms or animalcules 

 appeared.^ In these and all subsequent experiments 

 — including those of Pasteur and of Tyndall as 

 recently as thirty years ago — nothing was really 

 proved : because when animalcules did appear the 

 obvious explanation was that the sterilisation was 

 imperfect ; whilst when they did not appear after 

 heating the still more obvious retort was that the 

 process of sterilisation destroyed not merely pre- 

 viously existing life ; but also the conditions by which 

 life in ordinary circumstances could possibly have 

 originated. 



The only case which seems conclusive, then, is that 

 when living forms arise which it could be proved would 

 not have stood the temperature to which they had 

 1 See Huxley, loc. cit. 



