314 PROFESSOR LISTER ON THE GERM THEORY 
exception to the general law of living beings, that they originate from similar 
beings by parentage. 
Of those who oppose this theory, some attribute the changes to the oxygen 
of the air; others, while convinced of the insufficiency of the oxygen theory, 
hold the doctrine of so-called chemical ferments, and ascribe the alterations we 
are considering to organic principles destitute of vitality, the organisms being 
regarded as accidental accompaniments ; while others, admitting perhaps the 
fermentative agency of the organisms, believe that they do not necessarily 
spring from parents like themselves, but may arise, de novo, from the organic 
world by spontaneous generation. 
The philosophical investigations of Pasteur long since made me aconvert 
to the Germ Theory, and it was on the basis of that theory that I founded the 
antiseptic treatment of wounds in surgery. The results of the treatment pur- 
sued constantly on this guiding principle have convinced me more and more of 
the truth of the theory upon which it was based ; and if I were to put together 
the facts which I have had presented to me in surgical practice, proceeding on 
the antiseptic system, I should be able to present an array of evidence in favour 
of the Germ Theory as good and convincing as experiments performed in a 
laboratory. 
But whilst I was thus for my own part thoroughly convinced of the truth of 
the Germ Theory of fermentative changes, I was led about a year and a half 
ago to direct my attention again to the subject by a remarkable paper by Dr 
Burpon SANDERSON, which appeared as an appendage to a report by the Medical 
Officer of the Privy Council.* Dr Burpon SAanpeErson produced evidence, of 
which the following may be taken as a specimen :—If a vessel like a miniature 
ale-glass was heated considerably above the boiling point of water, to destroy 
any organisms adhering to it, and, when cooled sufficiently, was charged with 
boiling PasTEvr’s solution,—a fluid ingeniously devised by that eminent chemist 
to provide suitable pabulum for organisms, consisting of a solution of cane- 
sugar, some ammoniacal salt, and earthy materials derived from the ashes of 
yeast,—the liquid being left freely exposed to the air, fungi developed in it, but 
no bacteria. If, on the other hand, a drop of water, say water from the tap, 
was introduced into the PAstrreur’s solution, within a few days the originally 
transparent liquid was rendered milky by the presence of abounding bacteria. 
Another very remarkable fact is mentioned by Dr Burpon SAanpErson in the 
paper referred to. These bacteria, which have been commonly regarded as 
tough-lived organisms, difficult to kill, were found by him to be deprived of 
vitality altogether by simply drying them thoroughly at a temperature no 
higher than that of an incubator for the hatching of eggs, about 100° F. 
* This paper will also be found in the Quarterly Journal of Microscopical Science, vol. xi. 1871. 
