LOUIS PASTEUR. 233 



beautiful crystallisation of left-handed tartrate of ammonia ". 

 If, however, he allowed the fermentation to continue 

 beyond this point the whole of the tartrate was broken 

 down. It was evident, then, that in this case these minute 

 organisms have a power of selecting the special form of 

 tartaric acid and that they have a preference for this, 

 although, when this special form is used up, they fall back 

 on the other and break it down in the same way as they 

 have already used up the first. 



In continuing these experiments, Pasteur made the first 

 of that series of experiments by which he was able to 

 corroborate Schwann's experiments designed to prove that 

 no life could be generated from dead organic matter, but 

 that, if certain organisms gained access, even to special forms 

 of inorganic matter, they were capable of multiplying freely ; 

 he was able to show that the spores of the Penicillium 

 glaucum, or common mould, could grow and produce the 

 fully formed mould, in a solution of paratartaric acid — to 

 which nothing but phosphates of potash, of magnesia, and 

 an ammoniacal salt of an organic acid had been added — 

 first using up the right-handed tartrate and then attacking 

 the left. 



Liebig and Gay Lussac had both taught that fermenta- 

 tion and decomDosition were due to the action of the oxvsen 

 of the air upon nitrogenous substances, and that this process 

 was due to the initiation of certain molecular movements 

 by this process of oxidation, these movements being gradu- 

 ally communicated from particle to particle of the ferment- 

 able substance, which was thus resolved into the products 

 of fermentation. Others — Berzelius and Mitscherlich — 

 explained fermentation as the result of the action of a 

 nitrogenous ferment which exerted a catalytic action by 

 its mere presence, adding nothing to the solution and 

 taking nothing from it, but exerting its influence by what 

 these philosophers termed the phenomena of contact. 

 Pasteur was satisfied with neither explanation. Caignard- 

 Latour and Dumas — Pasteur's teacher — both associated 

 the growth of the yeast-cell in organic solutions with the 

 process of fermentation that accompanied this growth. 



