298 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



of the writers were vague and confused in the extreme. Perhaps 

 the first philosophical explanations put forward were those of the 

 German philosopher, Stahl (16G0-1734) and of the English physi- 

 cian, Thomas Willis, who described himself as " of Christ Church 

 in Oxford, and Sidley Professor of Natural Philosophy in that 

 famous University." According to their view, fermentation is 

 considered to be an induced action — that is to say, the ferment is 

 a body endowed with a particular molecular motion, which motion 

 is, by induction, communicated to other bodies with which it may 

 be in contact, thus bringing about their decomposition. Thus, 

 Willis in his tract, "De Fermentatione " (1600), says: "Fermenta- 

 tion is the internal motion of particles, or of the principles of a 

 body, either tending to the perfection of the same body, or its change 

 into another. * * * There are many methods by which fermen- 

 tation may be induced. The first, the chief one, is the adding of 

 a certain ferment to the body to be fermented, the particles of which 

 being first placed in vigour and motion, may arouse the other slug- 

 gish and idle particles in the mass that is to be fermented, and may 

 drive them into motion. * * * ]5y this means Barm or Yest, 

 beaten eggs and such like, stir up a fermentation almost in every- 

 thing." But in spite of the clearness of these statements, Willis, 

 like the other philosophers of his time, included putrefaction, the 

 formation of minerals in the earth, and a vast number of other 

 natural phenomena under the general term " fermentation." 



The next important attempt to explain the nature of fermenta- 

 tion w-as made in 1839, when the great German chemist, Liebig, 

 put forward a theory which was a modification of that of Stahl 

 and Willis. Liebig asserted that nitrogenous matter on oxidation 

 underwent a change which determined the breaking up of the 

 molecules of fermentable matter in contact with it, and laid con- 

 siderable emphasis on the importance of the presence of oxygen. 

 This theory of contact decomposition as the result of molecular 

 vibration held the field for more than 30 years, but during the 

 latter part of its life it was vigorously attacked by Pasteur, who 

 was then engaged upon his epoch-making biochemical researches. 

 The controversy was a long and vigorous one, and in the end 

 Liebig modified his original views to the extent of admitting that 

 the fermentation process was in some way connected with the life 

 activity of the organism producing it, but he adhered so far to his 

 earlier view as to hold that this life activity was not in itself the 

 exciting cause, but was only necessary for the formation of some 

 protein like substance which actually brought about the decom- 

 position. This theory, which was put forward shortly before his 



