FERMENTS, FERMENTATIONS, AND LIFE. 551 



what the illustrious Ehrenberg calls the milky-way of lower organ- 

 isms, and no less essential for explanation of the processes of which 

 we have traced the general course. As there is an ether wanting in 

 life, so there is an ether endowed with life — a vital ether. Both are 

 above denial ; they surpass our reason, yet reason cannot but demand 

 them. They elude the close grasp of experiment, yet experiment does 

 not permit them to be avoided ; they are unseen, and without them 

 there could be nothing seen. The mind clings to them with the stress 

 of all its power to embrace, perhaps because it feels a secret, mysteri- 

 ous affinity with them, perhaps because it is in substance of the same 

 essence with them. 



III. 



OuK atmosphere, then, is the receptacle for myriads of germs of mi- 

 croscopic beings, which play an important part in the organized world. 

 Penetrating agents of decay, baneful toilers for disease, they lie ever 

 in wait for the chance to pierce the internal machinery of animals and 

 plants, and create slight or grave disturbances within it. Life often 

 resists or escapes them, but nothing can contest with them its deserted 

 vesture. The corpse is their natural aliment, and death their chosen 

 laboratory. There these lowest of created things work out their lofty 

 destiny in the eternal drama of renewal of organic existences. 



When the thin pellicle covering sweet fruits is torn at any point, 

 an opening is made for atmospheric germs. Fermenting cells pierce 

 the interior of the fruit, and produce within it fermentation of the su- 

 gar, that is to say, the formation of a little alcohol ; and this in its 

 turn is susceptible of the passage into acetic fermentation, giving the 

 pulp an acid taste. At last the pulp itself is destroyed by various 

 fungous growths. When a fruit decays and takes a more or less un- 

 pleasant flavor, this depends on the intervention of ferment-cells of at- 

 mospheric origin, and on the production of acid or alcoholic substances. 

 An able micrographist, M. Engel, who has lately studied these phe- 

 nomena minutely, discovers that the yeast-cells which thus produce 

 alcoholic fermentation in the juices of fruits present some slight differ- 

 ences in various fruits, neither do they have the same morphological 

 character as those of grape-must or beer-wort. Varieties occur in 

 these cases, corresponding to the different media in which the nutri- 

 tion of the little fungus takes place. 



The microscopic fungi of the atmosphere play as interesting a 

 part in the alteration of wines. These grow acid, change, become filmy 

 or oily, or take on besides a decided bitterness. All these sicknesses 

 depend on the development of different little plants recognized and 

 described by M. Pasteur; and this scientist, not stopping at the solu- 

 tion of the nature of these disorders, has sought the means of prevent- 

 ing them. Resting on some former observations by D'Appert, he con- 

 ceived the idea of subjecting wines to the action of a very high degree 



