800 Teaxsactioxs of the American Institute. 



As chemistry advanced, facts came to light which put a new face 

 upon Stahl's hypothesis, and gave it a safer foundation than it pre- 

 viously possessed. The general nature of these phenomena may be 

 thus stated : A body, A, without giving to or taking from another 

 body, B, any material particles, causes B to decompose into other 

 substances, C, D, E, the sum of the weights of which is equal to the 

 weight of B, which decomposes. 



Thus, bitter almonds contain two substances, amygdalin and synap- 

 tase, which can be extracted, in a separate state, from the bitter 

 almonds. The amygdalin thus obtained, if dissolved in water, under- 

 goes no change ; but if a little synaptase is added to the solution, the 

 amygdalin splits up into bitter almond oil, prussic acid and a kind 

 of sugar. 



A short time after Cagniard de la Tour discovered the yeast plant, 

 Liebig, struck with the similarity between this and other such pro- 

 cesses and the fermentation of sugar, put forward the hypothesis that 

 yeast contains a substance which acts upon sugar, as synaptase acts 

 upon amygdalin ; and, as the synaptase is certainly neither organized 

 nor alive, but a mere chemical substance, Liebig treated Cagniard de 

 'la Tour's discovery with no small contempt, and, from that time to 

 the present, has steadily repudiated the notion that the decomposition 

 of the sugar is in any sense the result of the vital activity of the 

 Torula. But, though the notion that the Torula is a creature which 

 eats sugar and excretes carbonic acid and alcohol, which is not 

 unjustly ridiculed in the most surprising paper that ever made its 

 appearance in a grave scientific journal,* may be untenable, the fact 

 that the Torulce are alive, and that yeast does not excite fermentation 

 unless it contains living Torttlce, stands fast. Moreover, of late years, 

 the essential participation of living organisms in fermentation other 

 than the alcoholic, has been clearly made out by Pasteur and other 

 chemists. 



However, it may be asked, is there any necessary opposition between 

 the so-called "vital" and the strictly physico-chemical views of 

 fermentation ? It is quite possible that the living Torula may excite 



* " Das entrathsclte Geheimniss der Geistigen Gahrung (Vorlaufige briefliche Mittheilung) " is the 

 title of an anonymous contribution to Wohler and Liebig's " Annalen der Pharmacie" for 1839, in 

 which a somewhat Rabelaisian imaginary description of the organization of the "yeast animals," 

 and of the manner in which their functions are performed, is given with a circumstantiality worthy 

 of the author of Gulliver's Travels. As a specimen of the writer's humour, his account of what 

 happens when fermentation comes to an end may suffice : " Sobald namlich die Thiere keinen Zucker 

 mehr vorflnden, so fressen sie sich gegenseitig selbst auf, was durch eine eigne Manipulation gesch- 

 icht ; alles wird verdaut bis auf die Eier, welche unveraudert durch den Darmkanal hingehen ; man 

 hat zuletzt wieder gahrungs-fahige Hefe, namlich den Saamen der Thiere, der ubrig bleibt." 



