We only know the fact: the reason we are ignorant of. The most minute portion of milk, paste, juice of grapes, flesh, or blood, in a state of fermentation or putrefaction, causes fresh milk, paste, grape juice, flesh, or blood, to pass into the same condition, when in contact with them.
In storing or packing fruit for future use why is it necessary to carefully remove every decayed specimen?
Because the decayed portions of one specimen will quickly communicate decay to the fresh fruit in contact with it, and soon the whole mass of fruit will become putrescent.
If in a vessel, or any other structure, one timber becomes decayed what course ought to be adopted?
It should be removed immediately, or the decomposition once commenced will in time affect the whole structure.
It sometimes happens that physicians, in dissection, are seriously poisoned by the slightest cut of a knife which has been used upon the dead body. The knife introduces to the healthy blood, through the wound, a minute portion of matter in the state of decomposition or putrefaction. This acts as a ferment, and causes the healthy matter in contact with it to pass into the same decomposed state. The action once commenced rapidly extends, until the whole body becomes affected, and death ensues. It is almost impossible to heal wounds of this character.
Why is it especially dangerous to eat fruit or meats partially decayed?
Because the decayed portions of the substance eaten are liable to induce the same condition in the healthy organs of the stomach with which they may come in contact.
Why do fruit preserves frequently turn sour?
Because, owing to the action of some fermenting substance present either in the fruits themselves or in the air, the sugar used in preserving is converted into alcohol, and the alcohol into vinegar.