223 ANNUAL OF SCIENTIFIC DISCOVERY. 



advanced a^c; of the last three knackers that died, one was sixty, another 

 seventy, and a third eighty-four." 



Such are some of the facts adduced by Dr. Parkin in support of his views, 

 and sanitary reform will not be aided by eluding or suppressing them. 

 Abridged from the London Review. 



RESEARCHES ON FERMENTATION. 



M. Pasteur, of Lille, has recently been awarded a prize by the French 

 Academy for his researches on fermentation, which throw much light on 

 this little-understood department of chemistry. 



He shows that the germ in which fermentation originates is a living sub- 

 stance, organic, not inorganic, as some suppose; and leads to the conclusion 

 that there is a remarkable analogy between fermentation and physiological 

 action. In fermentation with yeast, for example, there is a perpetual 

 renewal of the yeast, and, at the same time, certain curious relations appear 

 between vital phenomena and mineral substances. Introduce yeast globules 

 into a mixture composed of candied sugar, ammoniacal salt, and a phos- 

 phate, and the ammonia will disappear by transformation into the complex 

 albuminous matter of the yeast, while the phosphate gives itself up to form 

 new globules. One of the elements of yeast is carbon, and this, in the 

 present example, is derived from the sugar. M. Pasteur further explains 

 and illustrates the process of lactic fermentation, which most chemists have 

 considered as organic matter in course of alteration; but the lactic yeast is 

 now shown to be really an organized substance, composed of globules, which 

 are smaller than those of the yeast of beer. In the fermentation of tartaric 

 acid, a further discovery was made of a surprising nature : among substances 

 known to opticians, are right-handed and left-handed tartrate of ammonia, 

 so named from the direction in which their solutions rotate rays of light. 

 They have no effect on polarized light; but, in the experiments here referred 

 to, fermentation took place in the right-handed only, while the left-handed, 

 similarly prepared, did not ferment, but underwent a change in Avhich it was 

 found to act with energy on polarized light. 



The analysis of yeast given by M. Pasteur, on the authority of M. Payen, 

 is as follows : One hundred pints contain 62.73 of nitrogenized matter, 29.37 

 of cellulose envelopes, 2.10 fatty matter, and 5.10 mineral matters. From 

 this it is evident that the yeast plant can only grow where it can obtain a 

 due supply of nitrogenous and mineral matter. When, by the presence of a 

 salt of ammonia and phosphates, these conditions were abundantly supplied, 

 M. Pasteur found the development of the yeast plant rapid and the fermen- 

 tation exceedingly active; but when the growth of the plant could only take 

 place through the assimilation of albuminous substances that were already 

 appropriated, as in grapes, beet-roots, etc., the same processes went on, but 

 with diminished velocity. 



In most chemical works it is stated that alcoholic fermentation takes place 

 under two circumstances, in which yeast is added to pure solution of sugar, 

 or to a solution containing albuminoid substances. In the first the yeast is 

 said to act, but not to reproduce itself, as in the manufacture of beer; and 

 Liebig observes, that if the fermentation was a consequence of the develop- 

 ment and multiplication of the globules, they would not excite fermentation 

 in pure solution of sugar, which does not offer the essential conditions of 

 their vital activity. To this il. Pasteur replies, that his observations and 



