eding year the relative female liability
becomes greater. This is probably due to the habit of kissing maintained
among females, but more and more abandoned by boys from babyhood
onwards.

All these considerations suggest the importance of segregating the sick
in isolation hospitals. Of late years this preventive measure has been
carried out with increasing efficiency, owing to the better provision of
such hospitals and the greater willingness of the public to make use of
them; and probably the improvement so effected has had some share in
keeping down the prevalence of the disease to comparatively moderate
proportions. Unfortunately, the complete segregation of infected persons
is hardly possible, because of the mild symptoms, and even absence of
symptoms, exhibited by some individuals. A further difficulty arises
with reference to the discharge of patients. It has been proved that
the bacillus may persist almost indefinitely in the air-passages in
certain cases, and in a considerable proportion it does persist for
several weeks after convalescence. On returning home such cases may, and
often do, infect others.

Treatment.

Since the antitoxin treatment was introduced in 1894 it has overshadowed
all other methods. We owe this drug originally to the Berlin school of
bacteriologists, and particularly to Dr Behring. The idea of making use
of serum arose about 1890, out of researches made in connexion with
Mechnikov's theory of phagocytosis, by which is meant the action of the
phagocytes or white corpuscles of the blood in destroying the bacteria
of disease. It was shown by the German bacteriologists that the serum or
liquid part of the blood plays an equally or more important part in
resisting disease, and the idea of combating the toxins produced by
pathogenic bacteria with resistant serum injected into the blood
presented itself to several workers. The idea was followed up and worked
out independently in France and Germany, so successfully that by the
year 1894 the serum treatment had been tried on a considerable scale
with most encouraging results. Some of these were published in Germany
in the earlier part of that year, and at the International Hygienic
Congress, held in Budapest a little later, Dr Roux, of the Institut
Pasteur, whose experience was somewhat more extensive than that of his
German colleagues, read a paper giving the result of several hundred
cases treated in Paris. When all allowance for errors