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jects, more particularly among persons in areas of high tuberculosis
morbidity and mortality—e.g. children of tuberculous families,
students, nurses, and other young employees in general hospitals
and sanatoria where exposure is great and protection difficult.
Taking into account the difference in the clinical features of
tuberculosis in this country from those I noted in Scandinavia,
I felt that their work was highly encouraging. Few will question
Heimbeck's original assertion—for which he deserves the highest
credit—that tuberculin-negative nurses show a higher incidence
of tuberculosis than those who are tuberculin-positive. I was
privileged to see with him in Oslo a further extension of this work
which more than corroborated his earlier observations.
Nothing that I saw impressed me more than the work of
Professor Arvid Wallgren, now professor of paediatrics in Stockholm,
who has certainly been the pioneer of B.C.G. vaccination in
Sweden, having started his work in Gothenburg in 1926. His
confidence in the clinical value of B.C.G. remains undaunted
although he recognises its limitation and admits that it is not
of use except in primary lung tuberculosis. Unfortunately, even
Wallgren has, however, had little opportunity for control work.
With regard to the respective merits of B.C.G. vaccine and
the vole-bacillus vaccine of Wells of Oxford, which is a close
competitor of B.C.G., Wallgren's observations to me are not without
interest. He urged, from his own experience of vole vaccine, that
it would be of the greatest scientific interest and value if we in this
country were to use it. He gave me the impression that it would
eventually supersede B.C.G. I think there is good evidence of
the belief that both methods of inoculation (a) are harmless to
humans, (b) increase resistance to tuberculosis, and (c) are of value
only in tuberculin-negative subjects. B.C.G. has stood the test
of time in many countries and its harmlessness has been established
by its practical application on a large scale in many parts of the
world. Nevertheless, there is good evidence that the vole-bacillus
vaccine has the following advantages over B.C.G.: (a) it is apparently
a more potent immunising agent, (b) its virulence is more
stable (the varying virulence of B.C.G. in Norway, Denmark and
Sweden was noteworthy, and I was told on more than one occasion
that some of the strains were losing their virulence), and (c) there
is reason to believe that tuberculin allergy following vaccination
with it was greater and occurred earlier than that following B.C.G.