XXV1 INTRODUCTION 
found, or whether they always came from pre-existing organisms which had 
somehow or other gained admission to the fluids, had been warmly debated. 
Pasteur’s work, however, really struck the final blow at the doctrine of 
spontaneous generation, although many further convincing proofs were 
brought forward later by other experimenters, notably by Tyndall and by 
Lister himself. 
The information, then, which Lister obtained from studying Pasteur’s work 
was (1) that organic fluids which had been boiled but were still prone to the, 
development of organisms and to fermentative changes, could be preserved 
without any change if the air admitted to the material after boiling had been 
calcined, or filtered, or had been kept at rest so long, or reached the fluids so 
slowly, that all the dust had had time to settle; (2) that the organisms found 
in the decomposing fluids were not produced spontaneously by changes in 
albuminoid materials, for they might appear and grow in artificial fluids con- 
taining mineral substances only ; (3) that these organisms were present in the 
dust of the atmosphere, and in that deposited on surrounding objects ; and 
(4) that the decomposition of the organic fluids coincided with the develop- 
ment of these organisms. If they were absent, no decomposition occurred ; 
as soon as they were admitted and began to grow, fermentative changes 
appeared. 
This was the work to which Lister’s attention was called, and it is easy 
to imagine the flood of light thrown on the whole subject of decomposition in 
wounds by its perusal. Lister at once applied himself to the task of finding some 
means of preventing the development of these living organisms in wounds. He 
formulated the hypothesis that the inflammation and septic diseases which 
occurred after wounds were due to the putrefaction of the discharges of the 
wounds ; while this putrefaction was in its turn due to the entrance of living 
micro-organisms from the air, and from the dust on surrounding objects. He 
made the deduction that if the access of living organisms could be prevented, and 
their growth in wounds arrested without at the same time damaging the wounds 
seriously by the means employed for this purpose, an open wound would follow 
the same course as a subcutaneous injury. No doubt this first conception was 
incomplete, but it was thoroughly sound, and while subsequent work has enor- 
mously extended the facts, the basal idea that it is the entrance of organisms 
into the wound from without which produces the inflammatory and septic 
troubles, and that therefore the aim of treatment must be to exclude or destroy 
them or inhibit their growth, still remains the fundamental principle of 
the treatment of wounds. The great variety of bacteria which may enter 
wounds, their very different behaviour, their various pathogenic properties, 
