168 
PROFESSOR TYNDALL ON THE DEPORTMENT AND VITAL 
On the 1st of December, for example, infusions of beef, mutton, pork, herring, 
haddock, and sole were prepared, and introduced into six closed chambers, each con- 
taining three tubes. On the 5th of December the pork, beef, mutton, and haddock 
were all covered with a fatty corrugated scum. A seventh chamber, containing artichoke- 
infusion, prepared at the same time, was found on the 5th more turbid than any of the 
animal infusions, and equally covered with scum. In the animal infusions, indeed, the body 
of the liquid underneath the scum maintained a surprising brilliancy, the development of 
life being confined to the layer in immediate contact with the atmospheric oxygen. 
On the 5th of December the herring- and sole-infusions were both clear ; hut this was 
only a respite, for on the 6th white spots appeared on the latter, which extended until 
they covered the whole surface. The herring-infusion remained clear for a week, after 
which small specks began to appear on its surface. They never reached the develop- 
ment of the scum which coated the other infusions. It sometimes occurred to me that 
the oil of this fish exercises a certain antiseptic action. 
Last year I preserved infusion of herring perfectly pellucid for months, even in a 
chamber so leaky that the light could be seen through its chinks. I had, moreover, no 
failure with any of the animal infusions here enumerated. Last year they all remained 
sweet and clear ; this year, with far greater precaution, I failed to protect any of them 
from putrefaction. Reflection on these results, renders, I think, but one conclusion 
possible to the scientific mind. It will be loth to assume that mutton, beef, pork, 
haddock, herring, and sole had totally changed their natures, and contracted qualities and 
powers this year which they did not possess a year ago. But if the origination of the 
observed life be denied to the infusions themselves, there is but one other source to 
which it could be referred, namely, atmospheric contamination. 
It became, indeed, more and more obvious to me that, in consequence of increased 
virulence in the contagia afloat this year, liberties in the preparation of the infusions or 
defects in the construction of closed chambers which would have been of no moment a 
year ago were sufficient to ruin the experiments, and render nugatory the usual means of 
sterilization. Against such defects I continued to struggle. With a view to stopping all 
chinks and crannies which might permit of the entrance of contamination, I had some 
of the chambers carefully coated with oil-silk and others covered with three coatings of 
strong paint ; and as failure had attended my efforts to procure an uninfected atmosphere 
upstairs, I had the entire apparatus used for digesting, filtering, and boiling removed 
to a store-room at the base of the Royal Institution. The floor of the room was of 
stone, and it was covered by no carpet. Prior to going into it, moreover, I caused my 
assistant to remove the clothes which he had previously worn in the laboratory and to 
dress himself in others. The infusions prepared under these conditions were cucumber, 
melon, turnip, and artichoke, which, from beginning to end, were operated on below 
stairs. Two chambers were devoted to each infusion, and after the usual boiling in 
the chambers they were permitted to remain in the store-room throughout the night, 
being transferred to the warm laboratory next morning. 
