976 M. H. Hoffmann on Fermentation. 
decomposing liquids containing sugar, and evolving gas, or, with 
the addition of oxygen, of causing the corruption and putrefac- 
tion of other organic liquids, then, by protecting these liquids 
from the Fungi, we should be able to preserve them in an incor- 
ruptible state. On this point Schréder has made a series of re- 
markable experiments, from which it appears that the dust of the 
atmosphere is in almost all cases the cause of the decomposition 
of organic liquids which have been boiled. He has, however, 
half abandoned the suspicion which he entertained that the 
spores of Fungi played an important part in this, on observing 
that when the liquids had been heated the spores no longer 
induced decomposition ; and he has arrived at the result that the 
dust only produces this effect when the materials have been pre- 
viously in contact with the free air. M. Hoffmann, on the con- 
trary, believes that decomposition may be produced by means of 
the spores of Mucedinee (supposing that they are not killed 
thereby), by placing them for an hour in the midst of liquids 
heated to 214° F. 
Organic liquids, such as broth, saccharine solutions, glue- 
water, boiled apples, honey and water, &c. placed in test-tubes 
well closed with a cotton plug, and boiled for an hour, remained 
intact for three to eight months, notwithstanding the excessive 
heat of the summer of 1859. But the result of the following 
experiment was very different :—Before pushing in the plug of 
cotton, an iron wire of moderate strength was passed through 
it; to the lower extremity of this was attached a small glass 
tube, two inches long, closed at both ends, containing dry spores 
of the Fungus on which the experiment was to be made. A 
second iron wire, placed by the side of the former, was attached 
to the lower part of the small tube; when the liquid in the test- 
tube had been boiled, and become cool, this served to break the 
two extremities of the small enclosed tube, and thus place the 
spores in contact with the liquid surrounding them. If these 
spores belonged to Penicillium glaucum, they rose to the surface, 
and in a few days covered it with a thick carpet of Penicillium. 
With the spores of Ustilago carbo and Stachylidium pulchrum, 
or dried beer-yeast, fermentation does not occur, or is produced — 
very feebly, because the dried spores rise and float on the sur- 
face. If, in place of a small closed tube, an open tube be em- 
ployed, the boiling vapour alone is sufficient to kill the spores, 
and in this case the liquid undergoes no alteration. Thus, 
although such experiments cannot be performed without some 
of the spores contained in the atmospheric dust arriving at the 
liquid, they would be killed by the boiling. 
It has long been known that the dust of imhabited houses 
contains spores. If an organic liquid which has been boiled be 
