PASTEUR 237 



It was, after all, a chance observation which 

 constituted the first step! It was an observation, 

 too, which to most minds, even scientific minds, 

 might at that time have seemed trivial; but to 

 Pasteur it seemed as indeed it was of profound 

 significance. The Cambridge Medical School has 

 done well to inscribe upon its new buildings a saying 

 due to Pasteur himself, "Dans les champs de 

 I 'observation le hasard ne favorise que les esprits 

 prepares" 



When a solution of a salt of tartaric acid in 

 the form spoken of above as racemic had stood 

 in his laboratory long enough to go 'mouldy,' or 

 to undergo fermentation, Pasteur found that, of 

 the two forms of tartrate present, one, and only 

 one, had disappeared. We have seen that the two 

 forms differ as little as does the right hand from 

 the left, and yet the growth of the mould, or the 

 action of the ferment, destroyed the one and left 

 the other untouched. Why ? The question greatly 

 stirred the mind of Pasteur. Materials for its 

 answer are woven in the very fabric of life itself. 

 No discussion of it must be attempted here. We 

 have only to note that the circumstance was 

 sufficient to fix the attention of the great chemist 

 and crystallographer, once and for all, upon the 

 subject of fermentation. Further happy chance 

 gave him, at the very time these observations were 

 made, work and duties at Lille, the centre of a 

 district where fermentations were a prominent 



