300 Miscellaneous. 



On Fermentation. By Prof. E. Mitscherlich. 



Fermentation is effected by a vegetable, putrefaction by an animal 

 production. In the course of the two last winters the author ob- 

 served in a large number of putrefying substances only one species 

 of Infusorium to be developed, which consisted of one or of several 

 globules, in the latter case arranged in series ; the diameter of such 

 globules was about 0*001™™, the motion vibratory. According to 

 his observations it would seem probable that the other animalcules, 

 wliich are observed in putrefying substances, have been conveyed 

 into them by means of the atmosphere, insects, or some other means. 

 A certain quantity of oxygen is requisite for the development and 

 existence of these Vibriones, and the putrefactive process is depend- 

 ent, according to the author, on the free access of a certain amount 

 of atmosphere to the decaying substances. The maceration of 

 vegetable substances in water, even when the temperature in the 

 rooms is kept at a summer heat, appears to depend solely on these 

 Vibriones, when the substances are employed in a clean state. Du- 

 ring this process nitrogen is disengaged. These Vibriones are widely 

 diffused in the intestinal canal throughout its entire course, in the 

 cavity of the mouth, and in the stomach, of which it is very easy to 

 be convinced by examining under the microscope the matter which 

 collects or remains on the teeth ; sometimes they are even found on 

 the skin, but the author has hitherto not succeeded in detecting 

 them in the blood, in the milk, in urine, in the gall, or in other 

 fluids of this kind. 



When a little sugar is added to the liquid in which these animals are 

 formed, their number augments considerably, and at the same time a 

 vegetable production is generated, viz. ferment. If a larger amount 

 of sugar be added, the production of these animals is suspended or 

 ceases entirely, and a greater quantity of ferment is formed. The 

 author has never observed ferment to be formed in a liquid which 

 contained no sugar. Whether a fungus be the fermentative fungus 

 or another species, may be determined with certainty under the 

 microscope ; but also very easily by adding some of it to a solution 

 of sugar, and observing whether any fermentation ensues. In a clear 

 liquid, in which it is possible for ferment to be produced, a turbid- 

 ness is first perceived, and under the microscope globules of various 

 sizes, from the smallest dimensions hitherto observed up to a diameter 

 ofO'Ol™™. From day to day the small globules increase in size, 

 and many new ones become apparent. In some liquids, as for 

 instance in the juice of the grape, only a few individual globules are 

 observed, which are generally of an oval form ; and sometimes, but 

 rarely, a second is developed at one of the extremities, but this 

 never attains to the size of the primitive globule. Ferment which 

 has been produced for some time by means of other ferment is 

 otherwise circumstanced ; from having been multiplied through a 

 series of years it has acquired a constant character. In the breweries 

 two kinds of ferment may be distinguished with certainty, the bottom 

 ferm.ent and the top ferment. The former multiplies at a tempera- 



