160 
PROFESSOR TYNDALL ON THE DEPORTMENT AND VITAL 
infusion was scumless throughout, while in the other each of the three tubes was heavily 
laden with scum. 
The two chambers containing the alkalized infusion of dried London hay had all 
their tubes turbid and covered with scum. In the case of the acid infusion of dried 
hay, the tubes of one of the chambers became turbid, while the tubes of the other 
chamber remained clear. 
The two chambers of alkalized new Heathfield hay-infusion were also in disaccord. 
In the one chamber all three tubes became turbid and covered with scum, while in the 
other chamber the three tubes remained sensibly clear and free from scum. Nor did 
the three tubes of the single chamber charged with the new Heathfield acid infusion 
present the same appearance; for while one tube became thickly turbid, the other two 
remained perfectly pellucid. 
Amid this confusion, the only point worth dwelling on is, that while no single case 
of escape occurred with the old-hay infusion, whether acid or neutral, with the infusions 
of both dried and undried new hay a certain percentage of the tubes remained sterile. 
Reflection on these results naturally drew suspicion upon the chambers. They had 
been used before, and, though carefully cleansed, some unobserved source of infection 
may have clung to them. This, at all events, seemed the most rational way of 
accounting for the differences observed between samples of the self-same infusion 
placed in different chambers. Hence my desire to expose a fresh series of infusions in 
chambers which had never been used before. 
Six new ones were therefore constructed, each of them containing six tubes. These 
were charged on the 3rd of November with infusions of old London hay, old Heathfield 
hay, new London hay, and dried London hay. Two chambers were devoted to each 
infusion, which in the one chamber was neutralized and in the other unneutralized. 
The six tubes in each chamber were arranged in two rows of three tubes each. Those 
nearest to the glass front were called the front tubes, the others the back tubes. The 
infusion intended for the unneutralized chamber was unboiled before its introduction 
into the three back tubes, and boiled in those tubes for five minutes afterwards ; the 
infusion for the front tubes was boiled for fifteen minutes before introduction and for five 
minutes afterwards. These differences in the mode and period of boiling were adopted to 
ascertain whether they had any influence on the subsequent development of life. In 
the case of the neutralized chambers, the infusion for the three back tubes was boiled 
for fifteen minutes outside before neutralization, and five minutes in the chamber after 
neutralization. The infusion for the three front tubes was boiled fifteen minutes out- 
side after neutralization, and five minutes afterwards in the chamber. If the potash 
used for neutralization carried germs into the infusion, the difference between five and 
twenty minutes in the period of boiling might, it was thought, declare itself in the 
subsequent phenomena. 
Four days after its introduction the old Heathfield acid infusion was found turbid 
