580 THE POPULAR SCIENCE MONTHLY. 



and that it is by carrying off a portion of oxygen from the last that 

 the ferment causes the fermentation to commence the equilibrium 

 between the principles of the sugar being disturbed, they combine 

 afresh to form carbonic acid and alcohol." 



The three views here before ns may be familiarly exemplified by 

 supposing the sugar to be a card-house. According to Stahl, the fer- 

 ment is somebody who knocks the table, and shakes the card-house 

 down ; according to Fabroni, the ferment takes out some cards, but 

 puts others in their places ; according to Thenard, the ferment simply 

 takes a card out of the bottom story, the result of. which is that all the 

 others fall. 



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 sub- 

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

 of B, wdiich decomposes. 



Thus, bitter almonds contain two substances, amygdaline and syn- 

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

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

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

 amygdaline splits up into bitter-almond oil, prussic acid, and a kind of 

 sugar. 



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

 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 amygdaline ; 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, 1 may be untenable, the fact that the Tondm are alive, 



1 " Das entriithselte Geheiinniss der Geistigsn Gahrung (Vorliiufige brieflichc Mitthei- 

 lung)" is the title of an anonymous contribution to Wohler and Liebig's " Annalen der 

 Pharmacie," for 1839, in which a somewhat Eabelaisian imaginary description of the 

 organization of the " yeast animals," and of the manner in which their functions are per- 

 formed, is given with a circumstantiality worthy of the author of " Gulliver's Travels." As 

 a specimen of the writer's humor, his account of what happens when fermentation comes 

 to an end may suffice : " When the animals find no longer any sugar, they devour one 

 another ; and this they do in a peculiar manner. They digest the entire animal, except- 

 ing only the eggs, which pass through the intestinal canal unchanged, and so the residu- 

 um is still a fermentable substance, viz., the sperm of the animals, which remains over." 



