DECEMBER 31, 1896] 
NATURE 
211 
The mouth is not guarded by a filter like the nose, but to a 
slight extent at least the saliva possesses disinfectant properties. 
The oral cavity is, however, never free from microbes, and some 
of them belong to highly pathogenic species, as e.g. the coccus 
of pneumonia, several forms of pus producing micro-organisms ; 
and the diphtheria bacillus has occasionally been detected in 
the mouth or on the tonsils without there having been any 
history of direct contact with diphtheria cases. 
These organisms may lead a saprophytic existence, and may 
remain harmless for a long time, till for some reason or another 
they are awakened to a life of virulent activity, Mr. Stephens 
and I have frequently found bacilli resembling the diphtheria 
bacillus in the dust, and though some of them are certainly not 
true diphtheria bacilli, others must be regarded with suspicion. 
Personally, after prolonged observations which I have carried 
on with Mr. Stephens at St. Bartholomew’s Hospital, I incline 
towards the view that the diphtheria bacillus is more widely 
distributed in space than is generally believed, and that ina 
harmless or saprophytic condition it may be inhaled and fix itself 
upon the tonsils. 
We have found in the air and on the surface of the body 
several varieties of bacilli, morphologically identical with the 
diphtheria bacillus. These are generally called pseudo-diphtheria 
bacilli. They are widely distributed. Some of them are so 
different in their biological characters from the diphtheria 
bacillus that they may be put on one side ; others, however, so 
closely resemble it that they cannot be treated with the same 
contempt. Some observers feel a peculiar satisfaction in hiding 
themselves behind the security of the pseudo-diphtheria bacillus, 
which is an undefined quantity, including many varieties of forms. 
No one nowadays ventures to define the cholera germ ; there 
are too many varieties of it. We believe that caution is advis- 
able in the diagnosis of the diphtheria bacillus. We have come 
to the conclusion that when a bacillus is morphologically 
identical in appearance with the diphtheria bacillus, and in its 
biological characters closely resembles the conventional type of 
the diphtheria bacillus, he must be a bold man who ventures to 
say off-hand that this bacillus is or is not a diphtheria bacillus. 
We know of no test-tube reaction or animal experiment which 
will always decide it. We believe that the diphtheria bacillus 
is found in nature as a saprophyte, and that under special condi- 
tions it becomes pathogenic, and then diphtheria results. We 
see once more, that in the mouth also pathogenic organisms may 
enjoy a harmless or non-pathogenic existence, until conditions 
arise which alter their character and render them virulent. 
We shall now pass on to a consideration of the bacteria which 
we eat and drink. 
That severe gastric and enteric lesions and derangements, 
often accompanied by the most severe symptoms, and occasion- 
ally followed even by death, are only too frequently the result of 
consuming unsound food, cannot be questioned ; and from the 
hygienic standpoint we, must insist upon the sale of proper and 
sound food, and upon a careful preparation of food. ‘* Food 
poisoning ” may be due :-— 
(1) To irritation, the food being good in itself, but indigest- 
ible or altogether unsuitable. 
(2) To bacterial infection ; or 
(3) To intoxication with poisons elaborated in the food. 
(4) To intoxication by poisons purposely or accidentally added 
to the food. 
Unfortunately, if we except the last cause of ‘‘ food-poisoning,”’ 
we have no sure tests which we can readily apply to gain infor- 
mation whether disease lurks in a tempting dish. We generally 
raise the cry of ‘‘death in the pot” after the mischief is done, 
and as a rule we do not get much further. Ina free and easy 
manner the analyst and the medical officer of health speak of 
ptomaines and toxines which they generally fail to detect, or it 
is stated that an appallingly large number of microbes have been 
found in the fatal dish—and this is often considered sufficient 
evidence to explain the distressing symptoms which ensued. 
The first point which I wish to make clear—or you may say 
to obscure—is the value of the quantitative bacteriological 
examination in cases of food-poisoning. 
In many reports we read that an unusually large nnmber of 
bacteria were found, and that amongst these were various forms 
of the Bacterzum coli commune or of Proteus. Now all such 
reports are somewhat unsatisfactory, unless we also know more 
of the circumstances under which the food was prepared or 
preserved, 
No. 1418, VOL. 55] 
First, as to numbers: what do they signify? Because we 
find 500,000 to a million, or even innumerable micro-organisms 
in a c.c. of fluid or in a minute particle of solid, can we, there- 
fore, always say, in the absence of other evidence, that as food 
such articles are unsound, and that such numbers account for 
the symptoms observed? I think not, because I can quote 
figures which prove that persons who never suffer or have 
suffered from food-poisoning habitually ingest enormous quanti- 
ties of bacteria without any evil accruing therefrom. 
(1) ALZk is constantly consumed by many individuals without 
harm. Now the best samples of milk that I ever obtained in 
London contained 250,000 micro-organisms per c.c. ; generally 
we find 1 to 24 millions per c.c., and if we let it stand at the 
ordinary temperature of the room these numbers may increase 
20 to 1000-fold. Yet such milk is generally harmless, and we are 
not justified in condemning it on account of the large number of 
germs present. It is impossible to obtain milk free from bac- 
teria, even if the cows were to be milked in a modern operating 
theatre, because the ducts in the teats always contain micro- 
organisms, which are washed into vessels, and there quickly 
multiply, and during the necessary exposure which must follow, 
more organisms find access to the milk. Mr. Parfitt has re- 
cently made some careful examinations of the bacteria present in 
London milk in my laboratory, and has found that 1 c.c. of milk 
contained 1,250,000 microbes, of which 303,000 were capable of 
growing at the temperature of the human body. I would, 
therefore, not undertake to condemn milk unconditionally, 
because I c.c. of it contained 500,000 to one million germs, and 
would hesitate to do so if it contained two, or even twenty, 
millions. Numbers here are not a true criterion ; hundreds 
and thousands of people consume milk teeming with bacteria. 
I do not say that there is no danger in milk, for we know that 
tuberculosis, enteritis, diphtheria, and scarlet or typhoid fever 
have often been traced to milk ; nor do I mean to say that the pro- 
cess of collecting and dealing with the milk could not be improved. 
These points are beyond our present argument. All I wish to 
show is that most of us consume habitually a large number of 
organisms without feeling any the worse forit. I do not recom- 
mend a bacterial diet, but I merely state the fact that we 
consume an enormous quantity of bacteria. 
I know very well that milk is a frequent cause of enteritis in 
children, especially during the hot summer months, and this. 
affection, which destroys the lives of many infants, is un- 
doubtedly frequently due to bacteria present in the milk. Prof. 
Fliigge’s experiments have practically settled this point, and 
we must agree that under certain conditions a considerable 
accumulation of bacteria in the alimentary tract can hardly 
be a matter of indifference. It is, however, difficult to 
say what the limit is, beyond which the ingestion of micro- 
organisms becomes dangerons ; and again it is possible, nay 
probable, that in many cases, for some reason or another, con- 
ditions arise which allow organisms existing in the gut, such 
as the &. col, to proliferate at a great rate, and thus to pro- 
duce most serious symptoms and intoxications. It is right and 
proper to avoid all dangers and risks by collecting and pre- 
paring food properly, by cooking it sufficiently, and by consuming 
no food that has been kept too long ; but it is equally right and 
proper to remember that some articles of food are not only con- 
sumed, but also relished, which are known to contain enormous 
numbers of micro-organisms. We cannot make our lives 
miserable by refusing all but sterilised food ; and I wish to point 
out to you,that some articles of food which we particularly 
enjoy are teeming with bacteria, and for all that are not to be 
condemned. The question is, how did the organisms find their 
way into the food, z.c. what are the causes and circumstances of 
the contamination ? : 
We are everywhere surrounded by danger, so far as bacterial 
infections are concerned. A slight scratch or a fall on the 
ground may be the cause of lock-jaw or tetanus. Are we, 
therefore, to give up all forms of exercise, such as football and 
bicycling? The friendly services of the bacteria outweigh the 
injuries which they inflict upon us, and I believe that just as in 
the world around us they do us many a good turn, so also in 
the world within us do they assist us. Possibly we could get 
on without them, but we do not know yet whether we could 
get on better without them than with them. Let us fight our 
foes, such as the organisms of typhoid fever and cholera ; but 
this can be done with coolness and common-sense, and insist- 
ence on cleanliness and ordinary precautions. 
