162 
NATURE 
[ApRIL 8, 1915 


In spite of this, as you know, Lister’s treatment, 
though hailed with acclamation abroad, met with a 
very ungenerous reception in this country. His com- 
patriots could not understand the great principle that 
underlay it. They said that there was nothing new 
in it, or, if there was, it was bad. They said that 
their results were quite as good as his, or, if they 
were not, it was only because he paid so much per- 
sonal attention to his cases. They gave the treatment 
silly names, showing that they had not grasped the 
meaning of it; at first it was the ‘‘ carbolic treatment,” 
now it was the ‘“‘spray and gauze treatment.’’ This 
last name was even adopted by Lister’s disciples, and 
thus the spray came to be regarded as a fetish to such 
an extent that anything which cast a doubt upon its 
infallibility sorely tried the tender faith of the con- 
verted. 
But increasing knowledge forced Lister to alter his 
own beliefs and greatly to modify his practice in the 
two particulars to which I have especially directed 
your attention. Thus he more and more diminished 
the strength of and the amount of his antiseptics; 
and, having become gradually convinced that infection 
from the air, far from being the greatest source of 
danger, was a negligible quantity, he gave up the use 
of the spray for good and all. 
We must now inquire how this came about. Lister 
always looked upon an antiseptic as a necessary evil, 
because he saw that anything strong enough to kill 
germs must damage the living tissues. Therefore in 
quite early days he tried to do without antiseptics 
altogether, or at all events to admit nothing of the 
sort to the wound after the operation was finished. 
He also recognised from the first that healthy-living 
tissues had the mysterious power of preventing the 
growth of micro-organisms; and that this protective 
power was diminished by anything. that lowered their 
vitality. He further pointed out that the vitality of 
the tissues varies in different individuals and in 
different parts, of the body, as is illustrated by the 
well-known fact that healing takes place more readily 
in infancy than in old age, and in the face than in one 
of the limbs. The true meaning of this power was 
not then known. The explanation was given by the 
marvellous discoveries of Metchnikoff which Lister’s 
own work prepared him to receive, when they were 
made known to the worid. ; 
Everyone now is familiar with the word ‘“ phago- 
cytosis,” but have you, ladies and gentlemen, really 
grasped its meaning? It is a sufficiently appalling 
thought that each one of us, who looks upon himself as a 
single individual, is only a huge joint stock company. 
We carry about with us millions and millions of other 
individual organisms—micro-organisms indeed—but 
each one endowed at least with life and definite indi- 
vidual functions. Some of them are apparently essen- 
tial to the success of our bodies as a going concern. 
Many, even of these, are only waiting for some inter- 
ference with the vitality of a part, or the whole, of 
our body, to afflict us with local or general disease, 
and finally to dissolve us into our elements. 
Metchnikoff showed how these malignant organisms 
are kept at bay. Our very own body is made up of 
cells, each of which has, so to say, its individual 
existence and its special functions—almost its special 
intelligence—a fact which Lister was one of the first 
to demonstrate. Hosts of these cells—Metchnikoff’s 
phagocytes—form, some of them, our main mobile 
army of defence. They are not like other defensive 
cells, such as those of the spleen and bone marrow, 
confined to their fortresses, though as a rule, they 
keep their allotted positions. But they can move 
along strategic railways to any special point of attack, 
and when they have reached it, there ensues a battle 
NO. 2371, VOL.295)| 



royal with the invading army of pathogenic organ- 
isms, which they try to swallow, and, it possible, to 
destroy. If they are successful, health is restored. 
It may mean the aborting of a cold in the head, the 
subsidence of a pneumonia, or the rapid healing of a 
cut. If, on the other hand, they are overpowered by 
the invaders, the catarrh may extend to the smallest 
bronchi, the pneumonia may end fatally, or the 
wound may suppurate with disastrous results. 
These illuminating facts turned the attention of 
surgeons into another direction; and seeing that 
everyone knew that the vitality of the phagocytes 
must be impaired by any mechanical or chemical 
injury, the tendency was to reduce the strength of the 
antiseptics and to trust more and more to the phago- 
cytes. Lister himself used weaker and weaker anti- 
septic lotions, but he never thought it wise to dis- 
pense with them altogether. Others, however, being 
| chiefly obsessed with the notion that chemical anti- 
septics diminish the power of the phagocytes, main- 
tained that their use should be altogether discontinued, 
and have adopted, or say they have adopted, a treat- 
ment which, though having the same object as 
Lister’s, is supposed to be founded upon a different 
principle. How far this is actually the case it will 
presently be our business to inquire. 
This was one of the reasons why it began to be 
said that Lister’s teaching, like the Old Testament, 
was obsolete, and must be replaced by a newer and 
more perfect gospel. 
We must now further consider how far the air is 
really a source of infection. In the early days it was 
said that the number of germs in the air was enor- 
mous. As a matter of fact, such a statement is still 
true, as is easily shown by exposing a plate of culti- 
vating medium in any rocm, say in the most up-to- 
date modern operating theatre. . 
It was also taken for granted that the large 
majority of germs were pathogenic—that is, disease 
| producing. But very little was known, in 1865, of 
the varieties of micro-organisms. It is true that 
Pasteur had isolated various yeasts or ferments, and 
had shown that some organisms were aerobic and 
some anaerobic, and that the words vibrio and bac- 
terium were beginning to be used. But as time went 
on two very important facts were made out. First, 
that only a small proportion of the flora of the air 
are pathogenic; and, secondly (and this was one 
of Lister’s own discoveries), that great dilution of a 
septic fluid very much diminished its chance of in- 
fecting a putrescible medium. ‘Thus typhoid pollution 
of the Nile in a few miles ceases to be a source of 
danger, and one or two septic organisms introduced 
into a vessel of blood serum will fail to grow. It is 
really masses of particulate dirt which are dangerous, 
because they contain colonies of organisms adequately 
protected from attack. And, if this applies to 
attempts at infection of vessels containing blood 
serum, still more does it apply to the dropping of 
isolated staphylococei and streptococci on to a wound 
where the greedy phagocytes are lying in wait to 
devour them. At every operation scores of germs 
fall upon a wound—hundreds if it be prolonged—but 
most of them are those of moulds and other innocuous 
vegetables which have no chance of growing there; 
and although there is a possibility of an occasional 
pathogenic organism being among the number, the 
risk of its developing is so small, that it is now gener- 
ally considered to be negligible, and that if one or two 
should escape into the lymph channel, they will never 
elude the phagocytes in spleen or bone marrow or 
elsewhere. ‘ 
I must now explain how the spray helped to prepare 
| Lister for the acceptance of Metchniloff’s discoveries. 



