THE PRESIDENTIAL ADDRESS. 9 
as antitoxic sera, and the most familiar examples are anti-tetanic and anti- 
diphtheritic. 
We have seen how the injection of living or dead bacilli or their toxins 
into animals gives rise to the production of antibodies or antitoxins. The 
blood serum of such animals in virtue of the antibodies contained in it 
can be used to combat disease. 
Let us take in the first place the case of tetanus, until recently considered 
to be one of the most fatal of maladies, at least 85 per cent. of the cases 
succumbing. 
As you are aware, anti-tetanic serum is prepared by injecting horses 
with large quantities of tetanus toxin. When the blood is as full as possible 
of antibodies it is drawn off and the serum allowed to separate out. 
The idea lying behind this third method of preventing disease is to 
pour in these ready-made antitoxins in order to assist the body in its first 
struggle with the invading disease, and give it, as.it were, a breathing space 
to prepare its own defences. 
Naturally the immunity produced by these antitoxic sera is of a passive 
nature, and of short duration, as compared with that produced by the 
disease itself, or even by the milder form brought about by vaccination or 
inoculation. 
Anti-typhoid inoculation will protect a soldier for, let us say, two years; 
anti-tetanic serum will protect for only a week or ten days. It is therefore 
impossible to inoculate a whole army against tetanus. It is necessary to wait 
until there is a danger of the disease occurring. 
To illustrate this I shall describe briefly the history of the prevention of 
tetanus during the Great War. 
When the British Expeditionary Force went over to France, in August 
1914, only a small quantity of anti-tetanic serum was taken, and that for 
the purpose of treatment rather than prevention. But shortly after the 
outbreak of hostilities the number of cases of tetanus among the wounded 
became so alarming that no time was lost in grappling with the danger. 
Large quantities of serum were hurried to the front, and some two months 
after the beginning of the war it was possible to make an order that every 
wounded man should receive an injection of anti-tetanic serum as soon after 
he was wounded as possible. Later on, after further experience had been 
gained, the single injection was increased to four, given at intervals of a 
week. This helped the wounded man over the dangerous time and the 
results were very successful. 
In August and September 1914, before the prophylactic injection was 
